SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549
                                  SCHEDULE 13G
                    Under the Securities Exchange Act of 1934
                                (Amendment No. )*

                                BLOCKBUSTER INC.
                                ----------------
                                (Name of Issuer)

                 Class B Common Stock, $0.01 Par Value Per Share
                 -----------------------------------------------
                         (Title of Class of Securities)

                                   093679 10 8
                                  ------------
                                 (CUSIP Number)

                                December 31, 1999
              -----------------------------------------------------
             (Date of Event Which Requires Filing of this Statement)

      Check the  appropriate  box to designate  the rule  pursuant to which this
Schedule is filed:

                  / / Rule 13d-1(b)

                  / / Rule 13d-(c)

                  /X/ Rule 13d-1(d)

      *The  remainder  of this cover  page  shall be filled out for a  reporting
person's  initial  filing on this  form with  respect  to the  subject  class of
securities,  and for any subsequent amendment containing information which would
alter the disclosures provided in a prior cover page.

      The information  required in the remainder of this cover page shall not be
deemed to be "filed"  for the purpose of Section 18 of the  Securities  Exchange
Act of 1934 ("Act") or otherwise  subject to the  liabilities of that section of
the Act but shall be subject to all other  provisions of the Act  (however,  see
the Notes).

                       (Continued on the following pages)

                                   Page 1 of 6



CUSIP NO. 093679 10 8

(1)   Name of Reporting Person
      S.S. or I.R.S. Identification No. of Above Person
      Viacom International Inc.
      --------------------------------------------------------------------------
      I.R.S. Identification No. 13-3844753
      --------------------------------------------------------------------------

(2)   Check the Appropriate Box if a Member of Group (See Instructions)

/ /   (a) ______________________________________________________________________
/ /   (b) ______________________________________________________________________

(3)   SEC Use Only _____________________________________________________________

(4)   Citizenship or Place of Organization                         Delaware
                                                               -----------------
---------------------
Number of                  (5)      Sole Voting Power               0
  Shares                                                       -----------------
Beneficially               (6)      Shared Voting Power             144,000,000*
 Owned by                                                      -----------------
   Each                    (7)      Sole Dispositive Power          0
Reporting                                                      -----------------
Person With                (8)      Shared Dispositive Power        144,000,000
                                                               -----------------
---------------------

(9)   Aggregate Amount Beneficially Owned by Each Reporting Person

                                    144,000,000*
      --------------------------------------------------------------------------

(10)  Check if the Aggregate Amount in Row (9) Excludes Certain Shares
      (See Instructions) _______________________________________________________

(11)  Percent of Class Represented by Amount in Row (9)
                                    100%
      --------------------------------------------------------------------------

(12)  Type of Reporting Person (See Instructions)           CO
                                                  ------------------------------

      (*each  share of Class B Common stock is entitled to five votes per share;
each  share of Class A Common  stock,  of which  the  Reporting  Persons  own no
shares, is entitled to one vote per share)

                                   Page 2 of 6



 CUSIP NO. 093679 10 8

(1)   Name of Reporting Person
      S.S. or I.R.S. Identification No. of Above Person
      SUMNER M. REDSTONE
      --------------------------------------------------------------------------
      S.S. No.
      --------------------------------------------------------------------------

(2)   Check the Appropriate Box if a Member of Group (See Instructions)

/ /   (a) ______________________________________________________________________
/ /   (b) ______________________________________________________________________

(3)   SEC Use Only

(4)   Citizenship or Place of Organization                         United States
                                                                   -------------
---------------------
Number of                  (5)      Sole Voting Power               0
  Shares                                                       -----------------
Beneficially               (6)      Shared Voting Power             144,000,000*
 Owned by                                                      -----------------
   Each                    (7)      Sole Dispositive Power          0
Reporting                                                      -----------------
Person With                (8)      Shared Dispositive Power        144,000,000
                                                               -----------------
---------------------

(9)   Aggregate Amount Beneficially Owned by Each Reporting Person

                                    144,000,000*
      --------------------------------------------------------------------------
(10)  Check if the Aggregate Amount in Row (9) Excludes Certain Shares
      (See Instructions) _______________________________________________________

(11)  Percent of Class Represented by Amount in Row (9)
                                    100%
      --------------------------------------------------------------------------

(12)  Type of Reporting Person (See Instructions)           IN
                                                 -------------------------------

      (*each  share of Class B Common stock is entitled to five votes per share;
each  share of Class A Common  stock,  of which  the  Reporting  Persons  own no
shares, is entitled to one vote per share)

                                   Page 3 of 6



Item 1. Identity of Issuer

      This Statement on Schedule 13G is filed by the undersigned with respect to
the Class B Common  Stock,  par  value  $0.01  per  share  (the  "Class B Common
Stock"),  of Blockbuster Inc. (the "Issuer").  The Issuer's principal  executive
offices are located at 1201 Elm Street, Dallas, Texas 75270.

Item 2. Identity of Reporting Persons and Background

      This Statement is filed on behalf of Viacom  International  Inc.  ("Viacom
International") and Viacom Inc. ("Viacom"),  each a Delaware corporation ("BVI")
with a principal  address of 1515  Broadway,  New York,  New York 10036;  NAIRI,
Inc., a Delaware corporation ("NAIRI") and National Amusements, Inc., a Maryland
corporation  ("NAI") and Mr.  Sumner M.  Redstone,  an  individual,  each with a
principal address of 200 Elm Street, Dedham,  Massachusetts 02026 (collectively,
the "Reporting Persons").

      Viacom International is a wholly owned subsidiary of Viacom. Approximately
67.7% of  Viacom's  voting  stock is owned by  NAIRI,  which in turn is a wholly
owned subsidiary of NAI; Mr. Sumner M. Redstone is the controlling  shareholder,
Chairman  and Chief  Executive  Officer of NAI and Viacom,  and the  controlling
shareholder, Chairman and President of NAIRI.

Item 3. If this Statement is filed pursuant to ss.240.13d-1(c)
        check this box / /.

Item 4.  Ownership.

      Each of  Viacom  International,  Viacom,  NAIRI,  NAI and  Mr.  Sumner  M.
Redstone  beneficially  owns the one hundred  forty four  million  (144,000,000)
shares of Class B Common  Stock  reported  hereunder,  representing  100% of the
outstanding  shares of Class B Common Stock.  Each share of Class B Common Stock
held by Viacom  International  or any of its  affiliates may be converted into a
share of the  Issuer's  Class A Common  Stock,  par value  $0.01 per share  (the
"Class A Common Stock") at such holder's  option;  under certain  circumstances,
such Class B Common Stock converts  automatically  into Class A Common Stock. At
December  31,  1999,  there  were  31,002,666  shares  of Class A  Common  Stock
outstanding.

      Holders of Class A Common Stock are entitled to one vote per
share and holders of Class B Common Stock are entitled to five votes per share.

      Due to the  relationship  of the  Reporting  Persons  described  in Item 2
hereof,  each of the  Reporting  Persons may be deemed to share with each of the
other Reporting Persons power (i) to vote or direct the vote and (ii) to dispose
or to direct the  disposition  of the shares of Class B Common Stock  covered by
this Statement.

                                   Page 4 of 6



Item 5. Ownership of Five Percent or Less of a Class.

        Not Applicable

Item 6. Ownership of Five Percent on Behalf of Another Person.

        See Items 2 and 4 hereof

Item 7. Identification and Classification of  the  Subsidiary Which Acquired the
        Security Being Reported on By the Parent Holding Company.

        Not Applicable

Item 8. Identification and Classification of Members of the Group.

        Not Applicable

Item 9. Notice of Dissolution of Group.

        Not Applicable

                                   Page 5 of 6



Item 10. Certifications.

      By signing below we certify that, to the best of our knowledge and belief,
the  securities  referred  to above were not  acquired  and are not held for the
purpose of or with the effect of  changing  or  influencing  the  control of the
issuer of the  securities  and were not acquired and are not held in  connection
with or as a participant in any transaction having that purpose or effect.

      After reasonable  inquiry and to the best of our knowledge and belief,  we
certify that the information  set forth in this statement is true,  complete and
correct. Pursuant to Rule 13d-1(f)(1),  we agree that this statement is filed on
behalf of each of us.

Date:  February 14, 2000                        VIACOM INTERNATIONAL INC.


                                                By:      /s/ Michael D. Fricklas
                                                         -----------------------
                                                         Michael D. Fricklas
                                                         Senior Vice President,
                                                         General Counsel

                                                VIACOM INC.

                                                By:      /s/ Michael D. Fricklas
                                                         -----------------------
                                                         Michael D. Fricklas
                                                         Senior Vice President,
                                                         General Counsel

                                                NAIRI, INC.

                                                By:      /s/ Sumner M. Redstone
                                                         -----------------------
                                                         Sumner M. Redstone
                                                         Chairman and President

                                                NATIONAL AMUSEMENTS, INC.

                                                By:      /s/ Sumner M. Redstone
                                                         -----------------------
                                                         Sumner M. Redstone
                                                         Chairman and
                                                         Chief Executive Officer

                                                By:      /s/ Sumner M. Redstone
                                                         -----------------------
                                                         Sumner M. Redstone,
                                                         Individually

                                   Page 6 of 6