Read the whole thread... We're talking about keying a few seconds in After Effects, not a live key. Yes of course, I would never recommend using a bedsheet for live keying, but AE is much more forgiving and gives you many more tools for pulling off a decent key with virtually any background.

The actual shot of the person getting hit by the car can be just a split second; in this case you can just rotoscope the person frame by frame. You wouldn't have more than 30 frames to do.

1. Long shot of person walking along, whatever, into the street
2. Medium shot of car oncoming
3. Closeup of person's face with fright
4. Split second shot of person getting hit by car, consists of footage of car speeding by, composited with a rotoscoped shot of person jumping in any odd fashion
5. Shot of person sprawled on the street, etc.

Thanks all!!! i figured out that I can use chroma key on Adobe Premiere, it doesnt come out as clean as AE but is much faster for me, any tutorials for chroma key on Premiere?