Blizzard has a fair-use clause with using images/video from World of Warcraft and other games since they support authors of Machinima movies.
You can make some cool screenshots in that game, even shots that only show a sunset or a green pasture.
I'm not sure if that would apply to Flash files on here since they clearly state you cannot sell your "videos" or anything you make inside the game. However, with our files, we don't sell the images.
From the terms:
"What is a content use license?
In the event that you are required to prove to the contest organizer, festival committee, or television broadcaster that you have Blizzard Entertainment's permission to use the images or video from World of Warcraft that appear in your Production, a content use license is provided. This license serves to prove you have the rights to use your Production materials specifically for that event."