Cynthia Gregory Dances Swan Lake

``A ballerina always looks like she is completely in control and could go on dancing forever.'' Gregory, throughout her long career one of the most distinguished American dancers, is well equipped to qualify this illusion and explain her preparation for the Odette-Odile role in the classic Swan Lake . Aided wonderfully by Swope ( Baryshnikov at Work ), a ballet institution herself, Gregory surveys a day's activity preceding performance, reviewing many details of interest to young balletomanes (``I am still nervous before a performance, even after decades of performing''). Clear, simple and pragmatic, Gregory's text ably serves the curious. In some cases, though, pictures are bound to tell the story best--as when the star's feet are coaxed into toe shoes far from glamorous, the feet show a remarkably primitive strength that is the means of its own transformation into onstage delicacy. Likewise, shots of Gregory making up are memorable for their candor and exoticism, proving that the ballerina is always a creature of beauty and artifice. Ages 8-12. (Oct.)