And actually because of the lighting in the room, the shadows/color variance doesn't make it a slam dunk operation. Although it certainly makes it easier. It's a fairly easy for a static image, but for video capture (which I tried), you have to turn your green-screen tolerance really high.
One of the great things about WOW was ModelViewer, a client side app that allowed you to view any model in the game and then animate them with the game's basic animations and you could place them on a green background. This is why WOW for a while had a massive surge in player-based machinima. The famous "hardware store" video, for example was done entirely with ModelViewer.
Camera manipulation in CO is causing me problems for movie creation. Also the combat tends to be over so fast, and is so fluid it makes capturing good snippets of video challenging. I'm still not consistently getting good screen shots with Genesis League outings, but as that improves and I get a better hang of it, I hope to then get better with video capture and build some nice video.
If there is/was a thread on CO machinima, I'd follow it and contribute.
For what it's worth (and I realise I'm late with this), there's a flat patch of neon green on a ledge halfway up one of the buildings in the Ren Center. Friend of mine used that for greenscreening with, and it worked okay.