As far as I know, it’s using the same H.264 codec that is also used by many Flash videos. The “crystal” clarity comes from higher resolution and less compression, and you could do the same thing with Flash, Quicktime, &c.
That maybe true, but everytime I see a video on silver light it always better than flash videos. It maybe that the users of silverlight understand; video, lighting, sound and encoding better, or just care more about what it looks like.
Or don’t have as many people watching, and can afford the bandwidth?
It was great using Silverlight to watch online video during the Olympics.
a) not everyone can install a native app or plugin. I expect web apps to work everywhere, on any device.
b) not everyone uses or will use a traditional pc.