What if your customers are watching a video on your site and their bandwidth is flaky? For the first five minutes they’ve got a solid high speed connection but then the bandwidth drops drastically. What happens to the video playback? Does it stall for a few seconds and then startup again?
Silverlight 2.0 will intelligently switch the video to low bandwidth streams when it detects the drop in speed. You need to to publish multiple streams of your video on web server to enable this behavior.