re: Serious question concerning shooting at a moving target (vid link added)

I would assume that if the chopper and truck are moving at the same speed, in the same direction (exactly) then your point of aim would be no different than stationary target with you firing from a stationary position as well. A bullet moving that fast at that short of a distance though, you are not likely to have to compensate much. Whatever compensation that would have to take place would depend on the choppers movements (direction and speed) relative to the truck, as well as the flight time of the bullet (distance between truck and chopper).

Just a disclaimer, I'm no expert on physics or anything, so I could be wrong.