In the language of hip-hop, the MC raps on top of the beats. The DJ--or turntablist--supplies the beats. Doug Pray's lively documentary is a tribute to these unsung heroes of the "scratch." His approach is neither dry nor academic and is designed as much for the masters of the form as for the fans. Pray was also behind Hype!, which focused on the Seattle scene in the 1980s and 1990s. In his 2002 follow-up, he travels as far back as the 1970s (DJ Kool Herc, Afrika Bambaataa) and roams the U.S. from New York (Gang Starr's DJ Premier) to the Bay Area (DJ Shadow, Q-Bert). After watching the film and grooving to the beat, you're likely to wonder if there's a soundtrack to accompany it. Fortunately, there is--Bill Laswell, producer of Herbie Hancock's seminal "Rockit," is behind a compilation featuring many of the same artists celebrated in Scratch. --Kathleen C. Fennessy