If you liked "That's Dancing," MGM's recent compilation of highlights from its fabulous musicals, then try the complete movies, just released on video. Warner Brothers had the gangsters, Paramount the comics, and Universal the monsters, but MGM dominated the musical field with the greatest song and dance stars ever assembled. Now THAT'S entertainment.

ON THE TOWN (MGM, 1949) Director Stanley Donen forsook constraining studio sets in favor of on-location shots for this cheerful romp about three sailors on weekend shore leave in Manhattan. Frank Sinatra croons and Gene Kelly hoofs, with attractive assistance from Vera-Ellen and Ann Miller.

SINGIN' IN THE RAIN (MGM, 1952) Possibly the best musical and one of the best films ever made. Donen and Gene Kelly co-directed and choreographed a brilliant, hilarious satire of Hollywood in talkies transition, which works even without the music. The fabulous numbers, including the legendary title routine, provide the coup de grace. Starring Kelly, Debbie Reynolds and Donald O'Connor.

SEVEN BRIDES FOR SEVEN BROTHERS (MGM, 1954) Donen returned to the studio for an Oregon timber-country version of the Sabine women. Seven logger brothers decide to increase their camp's female population, by seven. Pleasant and energetic, but nowhere near Donen's previous masterpiece, "Singin' in the Rain." With Howard Keel, Jane Powell, Russ Tamblyn and Julie Newmar.

GIGI (MGM, 1958) MGM wound up its film musical era with this classy production about young Leslie Caron's education in mistresshood in turn-of- the-century Paris. Tastefully directed by Vincente Minnelli from a novella by Collette. Featuring Louis Jourdan, Maurice Chevalier (singing "Thank Heaven For Little Girls") and music by Lerner and Loewe.

Other new MGM musical releases include: "Till the Clouds Roll By," "Bells Are Ringing," "Royal Wedding," "High Society" and "The Band Wagon."