Being a former broadcaster with the salary of an in demand programmer has really allowed me to stay in the loop with video gear and own "real" HD gear. (I have a Panasonic HVX200, for which the major expense is the solid state media.) It's funny how I've thrown a lot of convention out the door with regards to how I edit, since you're not constrained by the "package" mentality of broadcast news. Especially when you're dealing with fanboy type content, you can go with nice long cuts of stuff they just want to see.
In any case, I've been a QuickTime fan for many years. Back in the day, this was because the Sorenson Pro codec was easily the best in terms of quality. Then H.264 came around, and I declared it as the future years ago, back when most computers didn't have the nuts to even play it back.
These days, the action has been in Flash, for the obvious reason that it's so universally available. The recent adoption for Flash to playback H.264 QT movies makes it a total slam dunk for me. The primary benefit is one of work flow. It's easy to export these from Final Cut Pro very quickly.
I've started to play with Flash, the authoring application, to try and hack out a slightly customized video player. As an IDE for writing code, it absolutely sucks. ActionScript is not terrible, but I kept hitting obstacles in trying to get moving. So many articles online are behind subscriptions, and the documentation isn't organized very well. I'd kill for Intellisense.
Silverlight v2 has a lot going for it, though I haven't had any time to mess with it. I've barely touched Silverlight v1.x. Assuming that adoption skyrockets with the Olympics, I can see moving toward it for a lot of different reasons. Aside from being .NET-centric, the server-side of things have a lot of appeal. I remember the demo for the media server at Mix where they showed how you don't have to stream out the entire file too far in advance when there's potential that part of the video may never be watched. That's awesome stuff. The price is right too (free).
The only big negative to Silverlight as a video platform, for me, is the work flow issue. I can't quickly and easily get the video there out of the tools I use, and these are tools that the bulk of people in the field are using.
When I stop to think about it though, I left broadcast about nine years ago, and it's still not quite where I thought it would be with regards to video on the Internet. I mean that in terms of quality, which is no longer a function of CPU power, just bandwidth. Hopefully the US can catch up in that regard.