You are going to shoot high when you are higher up. on teh ground you are shooting striaght, from 15 up you have a different angle. All hunters who hunt from the stand encounter the same problem. just aim a little lower on the monster buck when he crosses your stand.
Absolutely WRONG
! Your making the classic mistake of dropping your arm instead of bending at the waist. If you bend at the waist and keep your form you will hit exactly where you intend to hit not high, not low, you pick a hair and you hit it.