Chroma key? I didn't shoot anything in front of a blue/green screen.
I just matchmoved a shot I filmed in my dorm hallway (with many curious onlookers wondering why I'm running full speed down the hall with a camera on a tripod) and imported the grunt Collada file into blender. I had to convert the .dds textures to PNGs first, but that was no biggie.
Hey I have to have these skills, it's not just a hobby for me, it's my LIFE!
EDIT: Oh and I had to rebuild the hall in CG and mimic the lighting... yea forgot about that little hiccup.