It's under enable_polycollision. It also says that setting it to 0 disables the physics engine, but I've been told that that is not the case. I haven't enabled physics in a while so I can't confirm that. Old collision is supposed to be removed one day, but that won't be for a long time, I'm sure. The c_instructions will be required if you use octree levels. Hijack over.

@destro55: Have you tried a video capture? I'm not sure if it'll pick it up with that, but you can try out Fraps.