In Amsterdam and Zurich, I presented a session called Building Your Own Video Site.  It was pretty cool, but sadly, the one hour we had to do the session, there was no real way to build the application up from scratch, so we just used a pre-built sample, and added some new UI and features to it. 

The site is available to play with today on the MIX07 servers at http://mixer1004.mixsandbox.com and you can see the slides and get the entire video from the MIX07 site.  I would include the slides that I used here, but the PPTX is about 10megs, so I'd suggest getting it from the MIX07 site where there's a bigger pipe, and more edge servers.