I found this fascinating quote today:
Explore is an excellent site for getting great educational videos. This site reminds me a lot of United Streaming but free. Once a person finds a video they are interested in they can either download it to their computer or view it on the web. These videos fall into different categories such as: environmental, human rights, health, philosophy, etc etc. Another great feature is that the films are broken down by grade level and there is a great photo area as well!!Dkapuler, Technology Tidbits: Thoughts of a Cyber Hero, Apr 2010
You should read the whole article.