One thing that absolutely sucks about looking for cc-licensed films and documentaries is that there's not really a lot of information about stuff that's been released, and there's really no actual robust organization that's promoting these works effectively.
Worse yet, Vimeo and YouTube offer ways to discover uploaded media with a specific license attached to it, but the reliability of the results is highly questionable. Vimeo doesn't even show the license on the video page anywhere.