If it’s Saturday night in Communist China circa 1972, you don’t have to think twice about where to go for a good time. No, literally: In the Cultural Revolution, the only entertainment permitted on stage and screen was the state-created yang ban xi, or revolutionary operas. This kitschy propaganda and its still-living practitioners form the subject of a fascinating but insidious documentary opening today at Film Forum.

The yang ban xi were the hard-line replacement of traditional Beijing opera imposed by Chairman Mao’s wife, Jiang Qing (aka Madame Mao). Adapted to film in a Technicolor of red cheeks and golden khaki, these tales of party-propping derring-do had titles like “Taking Tiger Mountain” and “The Red Women Detachment.”

Clips of the dancing soldiers and farmers appear in Yan Ting Yuen’s meandering documentary alongside interviews and verite jaunts. They sing revolutionary pap (“Today we who suffer will cast off our chains!”) and strike dynamic poses torn from posters. The dance-a-tronic moves involve an awful lot of urgent finger-jabbing, presumably in the general direction of Progress.

But anyone who’s snickered at the bushy-tailed youths in a Riefenstahl reel or at last year’s Film Forum doc “Hitler’s Hit Parade” knows the queasy feel to this kind of titillation. It takes only one detail to bring the kitschfest to a halt: An actress explains how apple slices were shoved into her cheeks so she would look fatter to the millions of peasants starving to death in countryside collectives. Stills of political executions later flash by with paltry explanation, their black and white overshadowed by the Crayola glitz.

Most of the artists who worked on them are nonetheless proud today, arguing understandably for the art, not the political arm-twisting. They were legitimate performers with no other outlet: a former composer speaks of how true art has wings and shouldn’t be held back. And in a priceless twist, one particularly jovial star is introduced shooting a commercial with the same loony grin of old.

Yet Ms. Yuen’s film is a little too amorally nostalgic about these artifacts of an earlier age, whose repression persists in streamlined forms. A fictional voice-over by Madame Mao borders on soap opera, but even more bizarre are the synchronized troops of modern-day teens who bust old-school moves for Ms. Yuen’s camera. It’s an ironic phenomenon worth investigating, but the everybody’s-doin’-it mindlessness has all the integrity of a rockumentary about how America was never the same after the Bee Gees.

The historical stakes, needless to say, are also a bit higher than the disco age (though the clothes are just as bad). It’s also hard to be encouraged by the director’s public responses to detractors, to the effect that they have no sense of humor and she just wants to show how the Cultural Revolution wasn’t all bad. True, you can’t stop irony, but forgetting history has the feel of the trapped coming to love the bars of their cage.

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