The TED Talks listed below are available under a Creative Commons license. For complete information about how TED Talks can be used, visit the TED Talks Usage Policy page.
The Library of Congress holds many collections that contain film and video. Though not all items within the collections are openly licensed or in the public domain (i.e. free of copyright), they are available online for educational and research purposes.
Below are links to a few of these collections, but there are many more on the Library of Congress' website at the above link.