Note: Please be careful with some of these resources; they may provide access to videos that are not appropriate for all audiences.
Google Video Search: http://video.google.com/
Yahoo Video Search: http://search.singingfish.com/sfw/home.jsp
Singing Fish: http://search.singingfish.com/sfw/home.jsp
Blinkx Video: http://www.blinkx.tv/
Truveo: http://www.truveo.com/
Unitedstreaming educational videos: http://www.unitedstreaming.com/