Australia's Science Forum

This is the site for TED Talks. These cover all different fields and are updated weekly. They are from 4 minutes to 18 minutes long. I search for science and technology related topics and have found some that staff find useful as an extension to classroom materials.
http://www.ted.com/

Lately I have downloaded talks on Deep Ocean Mysteries, Bioluminescence, Pollination, Inside the brain, brain beatbox, Secret Life of Plankton, Conception to Birth visualised. molecular machines.. there are many more on all science topics.