Our brains fill in lots of gaps by assumptions, in this case we are tricked.
Chris lifted the guy up via a harness and the black guy had a false right arm and a make-up covered real right arm which he pushed out as Chris lifts him up.
Timing is everything.
The black guy has to run off at the end to keep the illusion from being discovered, because if people were to touch him they would discover the false right arm and the harness.
The evidence has to be discarded quickly and then the man returns.
Were else have we seen the quick disposal of Evidence?