http://www.xbox.com/en-US/community/developer/rules
MLG and Rooster Teeth are fine though.
Update from Frankie
You may post your Item to a page or website that has advertising, but only if you do not earn any money from that advertising. For example, if you post your video on Youtube or Vimeo and there happens to be an advertisement next to it, then as long as you don't get paid for that advertisement, the fact that there is an advertisement on the page doesn't break these Rules. But enrolling in the Youtube partner program (or other similar programs), where you are entering into an agreement to get paid, is not allowed. On a similar note, if you create and distribute a free app, then you can't earn any money from advertising in that app.
MLG and Rooster Teeth are fine though.
Update from Frankie
These guidelines have been out there for months. How many of you are posting from jail? We'll get some clarifying messaging out there, but the legalese won't change, because it's legalese. We'll craft a path through the semantic minefield, however.
As I mentioned in the Halo community thread, these rules actually haven't really changed, and even the updated and clarified text has been up there for months. I assume somebody just noticed this and posted this morning because it sort of blew up. This has always been the Legal status for the IP (and MOST IPs in fact), and as you also already know, nobody is being sued, or in jail, etc etc etc.
The language isn't designed to stop kids streaming their games, or covering their costs, it's designed to stop big companies from using somebody else's IP to run a business.
We'll put together some language that will help community people navigate this easily, and give people workarounds.