"This library contains digital movies uploaded by Archive users which range from classic full-length films, to daily alternative news broadcasts, to cartoons and concerts. Many of these videos are available for free download."
Video in Critical Commons may well be copyrighted but the site encourages users to post and reuse content in keeping with fair use.
YouTube - Creative Commons Search
To limit your search on YouTube to videos licensed with Creative Commons, select "Filters" and "Creative Commons" under "Features." See this YouTube help page for more on licensing videos with Creative Commons.