As with most good sequels, this one includes a great deal that made the first one successful (show-stopping songs from hits as well as flops) as well as a few distinguishing features of its own: production numbers that were dumped (usually because the movie was running too long), reworkings of discarded scenes, footage of stars appearing in roles they never completed, testimony from one star whose career was harmed by institutionalized racism.

The show stoppers prove that there's still plenty of musical gold to be found in the MGM vaults. The statuesque, brassy-witted Dolores Gray's rendition of the Betty Comden/Adolph Green classic, "Thanks a Lot, But No Thanks" (from It's Always Fair Weather), makes you wonder why she never became a star. And whatever happened to Janis Paige, who's such a knockout performing Cole Porter's rowdy sendup of show-biz gimmicks, "Stereophonic Sound" (from Silk Stockings). Also well worth the price of admission: Doris Day's rendition of "Shakin' the Blues Away" (from Love Me or Leave Me), Mickey Rooney and Judy Garland teaming for "How About You" (from Babes on Broadway), Gene Kelly and Vera-Ellen dancing to "Slaughter on Tenth Avenue" (from Words and Music) and Fred Astaire and Cyd Charisse performing "The Girl Hunt" (from The Band Wagon).

The most breathtaking of the discarded scenes is an Astaire dance number, "I Wanna Be a Dancin' Man" (from 1952's The Belle of New York) that's presented side-by-side with the version that made it into the movie. Surely Astaire never dreamed that he'd be compared with himself this way, but what an extraordinary demonstration of the man's timing and grace this is!

In similar fashion, "Two Faced Woman," an Arthur Schwartz/ Howard Dietz song that was cut from The Band Wagon (1953), is compared with the version that made it into another MGM film from the same year: Joan Crawford's trashy backstage melodrama "Torch Song," in which Crawford lip-syncs the number in blackface.

Judy Garland's rendition of Irving Berlin's "I'm An Indian Too" never made it into the movie of Annie Get Your Gun (she was replaced by Betty Hutton), but the song was filmed and saved, and here it is, publicly presented for the first time.

Lena Horne sang "Can't Help Lovin' Dat Man" in the 1946 Jerome Kern biography "Till the Clouds Roll By," but Hollywood's nervousness about interracial romance prevented her from playing the character who sang it in MGM's 1951 film of Kern's Show Boat. Horne's gracious but stinging testimony about how Ava Gardner got the role could not be more effective. (We also get a sample of Gardner's fine singing voice, which was dubbed over.)

Horne is one of nine former MGM stars who introduce segments and talk about their experiences at the studio. Age has visibly slowed some of them down, but their enthusiasm and sincerity shines through, particularly when Rooney is talking about his adoration of Garland, or Allyson is remembering the years when she was star of Good News.

As with the previous installments in this series, the tendency toward hype and gush is undercut by just enough bizarre acknowledgments that the studio didn't always know what it was doing. An eye-popping musical contortionist act, the Ross Sisters, would not be out of place in Jim Rose's circus.

All the That's Entertainment! films insist that the golden age of the MGM musical ended with Gigi in 1958. But there were several high points after that date (Bells Are Ringing, Victor/Victoria, The Unsinkable Molly Brown, Viva Las Vegas). A fourth installment could easily go beyond Gigi and, like the 1985 MGM-based compilation That's Dancing, include clips from other studios' musicals.

Trimmed from a preliminary cut of 4 1/2 hours, this 115-minute contribution to the series was co-directed by Bud Friedgen and Michael J. Sheridan, who worked as editors on the 1974 and 1976 installments. George Feltenstein, who runs MGM/UA's video division, says much of the rare footage that was cut will soon turn up on laserdiscs.