The first quandary that comes to mind while watching the four-hour documentary American Roots Music is exactly what constitutes "roots." Early in the series—which aired on PBS before making its debut on home video—country singer Marty Stuart remarks that "disposable pop fluff" goes away, while traditional American music endures. But isn't disposable pop fluff also a part of the American musical tradition? Isn't it possible for contemporary musicians to be rooted in the music of David Cassidy, or Journey? Of course, those aren't the roots that American Roots Music filmmakers The Ginger Group (director Jim Brown, writer Charles Wolfe, and producers Brown, Sam Pollard, and Jeff Rosen) have in mind. Their documentary follows the story of the collection and popularization of folk songs, beginning with the flow of immigrants to the U.S. and the subsequent blending of instruments and musical forms from Europe and Africa. The documentary's best segments focus on the tradition of roots-music ethnography, which dates back to the turn of the century, when scholars traveled to the hills and fields to transcribe songs. The form blossomed in the early '60s, when protest singers and freshly scrubbed young people filled coffeehouses and concert halls with the songs they learned from Harry Smith's Anthology Of American Folk Music. The Ginger Group also digs up electrifying film clips of legends such as Bob Wills and Howlin' Wolf, although, as often happens with these sorts of projects, the film could stand more performance and less talking. American Roots Music follows the Ken Burns model, intercutting interviews with dynamic explorations of still photographs and snippets of archival footage, all connected by a basso profundo narrator (in this case, Kris Kristofferson). The pontificators include the likes of Bonnie Raitt, Mavis Staples, Pete Seeger, B.B. King, and Keith Richards, but they would have been better off exploring their roots connections through their instruments rather than their comments; a description of Doc Watson's banjo innovations isn't as useful as a demonstration. It doesn't help that some interviewees, like Raitt and Robbie Robertson, have a natural tendency to overstate the merits of the old-time players, as if to congratulate themselves on their taste. American Roots Music does contain pertinent observations, especially about the convictions and contradictions behind gospel music, and about the ways technological demands have shaped music's preservation and presentation. The final episode concerns the extension of antique musical forms into the plugged-in modern era, reinforcing the idea that Americana consists of more than the items gathering dust on the porches of small-town general stores. The wonderful music in American Roots Music attests to this notion, even if the snobby musicians don't.