Team Fortress 2 was awesome.
So what do you think is controversial about this? Gamers have been making fan-films for as long as I can remember, from basic screencapture of the monitor to extrracting 3d models from the game to throw into 3dmax environments.
Wolfenstein Online must be close to 15 years old now, and even then you could "record" your entire realtime battles into a textfile that could be emailed to others so they could watch your gameplay after the fact. You could even wander around the map, and view everything from whatever angle you wanted. Heck, in that game you could even create your own custom worlds to play in. Wolfenstein Toy Story-esque land & the Wild West were both a lot fo fun.
For a very creative look at game-movies, check out the Clear Skies videos, which uses a lot of Half-Life models (and their story engine) set in the EVE Online universe. Very witty & creative.
A lot of people will undoubetdly use these types of tools just long enough to catch a meme-wave, but there'll be a handful of really great imagineers (hope that's not copyrighted, Disney!) who can not only create a huge following for themselves, but spur interest (and fanbase) in the game they are modding.
Whatever. I'm rambling now.