The site offers alternative downloads of the video file. You should be able to watch these videos on linux with vlc or one of your favorite video players.
You need silverlight.
Ugh. They did this with the feynman lectures, too.
Edit: Jumped the gun. Just downloaded it as an mp4 to watch in vlc.
Ubuntu/FF28 - I was able to watch the video in browser without issue. I most definitely do not have Silverlight.