There is a great collection of videos at the website http://www.ted.com.
Science and technology are heavily represented, but there is a wide range
of videos for all interests. Videos can be downloaded in high resolution
to play back in class. There is some fascinating material here.
TED stands for Technology, Entertainment, Design. It started out (in 1984)
as a conference bringing together people from those three worlds. Since
then its scope has become ever broader.
The annual conference now brings together the world's most fascinating
thinkers and doers, who are challenged to give the talk of their lives (in
18 minutes).
This site makes the best talks and performances from TED available to the
public, for free. More than 200 talks from our archive are now available,
with more added each week. These videos are released under a [ http://www.ted.com/index.php/help#talks5 ]Creative Commons license, so
they can be freely shared and reposted.
Our mission: Spreading ideas. We believe passionately in the power of
ideas to change attitudes, lives and ultimately, the world. So we're
building here a clearinghouse that offers free knowledge and inspiration
from the world's most inspired thinkers, and also a community of curious
souls to engage with ideas and each other. This site, launched April 2007,
is an ever-evolving work in progress.