One highlight includes how they exposed everything on the site as a set of web services that can be mashed up into rich client apps or other web apps. You can do this simply by including thier video player in your blog post, but you cold also completely remix the site if you'd like. I also like how they include blog trackbacks in the conversation... and hopefully they track back to your blog site if there is a reply.
The second tidbit that stuck out is the dedication to dogfooding. The whole team is committed to delivering something they use and would want to use on a regular basis. They all blog, work on thier own sites, and participate in other online communities. It would be pretty hard to stay current in today's modern online world if your dev team isn't as commited as they are and using online sites for discussion on a regular basis. And I'm not talking about a blog that's updated every other month with your latest idea to "talk at" your customers.
The final bit from this video I loved was the breif discussion about the transition of discussions and the evolution of the venue over time. I actually used thier "clip" service to make a clip out of this segment. You can view the clip entitled "Community Evolution" here. This is for everyone who wonders why in the world we would have <gasp> web based forums for online discussion built into Visual Studio. It also begs the question of "What could you build into VS next to connect it to the community?"