Here's a not-so-good movie forwarding a good cause, freedom for Tibet from its captivity since 1950 by the current friends of American business, the Chinese Communists. Paul Wagner, a deservedly praised documentarian (Miles of Smiles, celebrating the unionizing of black Pullman porters; A Paralyzing Fear: The Story of Polio in America), shows no special facility as a director of narrative. He's not helped by his choice of an all-amateur cast to dramatize his too-schematic script about three young Tibetan relatives who follow three different courses regarding the Chinese.One becomes a Buddhist nun and Tibetan nationalist, devoted to the exiled, verboten Dalai Lama; another is a slacker shooting pool all day in the city; the third is a pop singer willing to sell her soul to the Chinese invaders with lyrics claiming the love of Tibetans for Chairman Mao. The characters' travails are predictable, as are the conversions of the two apolitical ones above to the cause of Tibetan liberation. OK, what's a Windhorse? A message on paper dropped off a mountaintop, which, catching a gust, ostensibly sails to the Tibetan gods.