"The Weather Underground"
It's sort of biased/sensationalized, but this is a really great documentary about the underground weathermen who participated in a bunch of protests and ultimately, pretty heavy organized crime in America during the Vietnam War. A lot of the figureheads are still alive, and do interviews for the film. I think there's even some aphex twin in the soundtrack to top it off..
PS. this isn't necessarily a film, but a short thing my old teacher put together last year about the history of film. http://www.youtube.com/watch?v=qVHXKzT_LB0
He's an older guy I respect a whole lot, and knows a whole poop-ton about the industry. Also, it's all edited to "Arrival of the Birds" by Cinematic Orchestra, if you're a fan of that sort of thing as well...