With the current trend of video games throwing in so much effort to advertise their mediocre game (*cough* Dante's Inferno *cough*), you think they would enjoy some free advertising, right? Some video games rely on this free advertising to get around, such as the mod DayZ being talked about by numerous content creators on Youtube. Apparently Microsoft doesn't want that free advertising for their games, and will make sure you don't earn any money off in-game footage in their games like Halo 4.
Microsoft has released an update to the Game Content Usage Rules for all their games. Any content creator that tries uploading a video using any game from Microsoft (Halo, Fable, Age of Empires) cannot make any money off advertisements surrounding the video. Other restrictions state that content creators cannot post it to sites that require a subscription fee to view it, or post it on a page that is used to sell other content or services.
So far the only video distribution sites Microsoft restricts is Vimeo and Youtube. They specifically stated that any partnership with Youtube or affiliate programs (like Machinima) will not be allowed.
I understand why Microsoft would do something like this. In some ways this allows them to control what can be distributed visually of their games to enhance the marketing for their product. For example, this might reduce the amount of trolls and griefers mocking their products if they can't earn any revenue from the advertisements.
But this also means Microsoft is not going to get any free advertisement from fans to their games. Minecraft and DayZ probably got so big because of the numerous videos on Youtube showing off these games. Surely when Halo 4 comes out, a fan will record their multi-player session to share it with other fans. But if the content creators are not going to get any revenue for it, they might as well play and record Borderlands 2 again, and share that content to their community.
I'm sure the numerous content creators out there will be glad to not give you any free advertising for your games, Microsoft.