Having recently discovered the black audiences Hollywood had neglected for years, Columbia Pictures decided to film the finale to the 1972 Watts Summer Festival, a daylong concert at the Los Angeles Coliseum that drew a crowd of 100,000. Seven years after the Watts riots brought “black power” into the public consciousness, the event celebrated racial pride and progress: Jesse Jackson tells the audience, “We changed ‘Burn, baby, burn’ to ‘Learn, baby, learn,'” and leads a rendition of “I am somebody.” This is much more than a concert movie; its rich tapestry incorporates documentary footage (the ’65 riots, interviews with Watts residents) that puts its musical performances (staged by Melvin Van Peebles) in a broad social context. The music is plentiful, with great gospel (the Staple Singers, Jimmy Jones), R&B (Albert King, Carla Thomas, Luther Ingram), and funk (Rufus Thomas, the Bar-Kays). But the real star is a young and scathing Richard Pryor (“How do the police accidentally shoot a nigger six times in the ass?”).