(OK so I'll post this but then I really really have to get back to work!)
I just got a note from the American Astronomical Society that many of the big lectures at the meeting in January 2008 were recorded, and are available online. Some are audio and some are video.
This is pretty cool. There are lots of interesting topics there, including extrasolar planets, galaxy formation, and star birth. The videos are in mp4 format (commonly called ipod format); however I can't seem to save them to my machine to play. Maybe you'll have more success.