I played along with NBC's fun experiment last night and downloaded Sarah Chalke's episode commentary.
It's really enjoyable (I'm a big fan of DVD commentary too) to listen along and get insights from the actors (like when Sarah pointed out Zach's stunt double carrying him during the crowd surf).
However (and it's a big however), it's near impossible to sync up the show and the commentary. The commentary has no markers and doesn't acknowledge commercial breaks. Also, I felt a bit silly with my laptop, lying in bed, trying to get all the pieces to work together. My wife was skeptical and fell asleep as usual halfway through the 2nd episode (a weekly occurrence).
I'd love it if NBC would broadcast a clean version on CNBC or make commentary with video available on iTunes. I guess I could Tivo the show, download to my PC and mix my own if I really wanted to. Totally not worth it.