1. This is not about replacing torrents. There wouldn't be much economic impact in that since that stuff is already stolen and in any case torrents are not on any CDN network. The point is that sites like youtube, hulu, and any other flash based video services (almost everything) will be able to operate at radically lower costs.
2. DRM has nothing to do with this protocol. You can implement DRM if you want. Its a separate layer. And many of the key content providers will want protection over their streams.
3. I dont know why it is "Non-Commercial" and "GPL infected" I don't know what that means. I would suggest that torrents are non commercial since there are no businesses offering their content via torrents and making money. That is, I believe, the definition of "commercial".
4. The issue of browsers needing to be open is a real one, though that only effects the level of effectiveness (i.e. cost savings). Most services deliver the most popular content most frequently. So at any given time, someone who's browser is open likely has all of or a part of a file that you want.