Videos from the U.S. Government : USA.gov
http://www.usa.gov/Topics/Video.shtml

USA.gov links to videos, video clips, movies, simulations, and public service announcements produced by United States federal government agencies, departments, and commissions. Most of these videos are available for use in the public domain; check the disclaimers on each website to determine if the image is in the public domain. This has been added to tools section of Research Resources Subject Tracer™ Information Blog.