Want to download and watch all PDC content? Then there are a couple of ways to get at them. The official way if to go through the session agenda at the conference site. See https://sessions.microsoftpdc.com/public/timeline.aspx. You see all sessions but it takes a bit of work. Another nice way is through Channel 9 by using the following feed: http://channel9.msdn.com/posts/pdc2008/RSS/?tag=videos.
But the best as far as I am concerned is using the list compiled by Greg Duncan. Check this list http://coolthingoftheday.blogspot.com/2008/10/pdc2008-quick-video-link-list.html. And it even has the Visual Basic source code used to generate the list [:)]
Enjoy the videos!