Sounds cool, right? What's the catch? The player is NBC only, and heavy DRM in there keeps it from playing anything else at all, including that scary "stolen copyrighted material." If you're going to use their player, you'll have to watch their shows, or else. I'd make a prediction that someone will hack it to play other stuff, but frankly, who cares. If NBC wants to go play in their own (non-Mac pool) let 'em, I say.
They also say that, in the future, they may even offer download-to-own, rental, and subscription business models. If only there was a well-designed, very established and compatible, widespread piece of software out there that let them easily do that right now. Oh well. Good luck, NBC. Say hi to Tina Fey for me, and tell her I'll see her on bittorrent.