I watched the video that was posted on this sight of the young hunter shooting the buck as he came by. It looked to me that the young man had confidence taking that shot. If you are confident, have practiced, know your set up, and once again, confident, then I see nothing un ethical about it. What would be un ethical to me would be someone that has not practiced shooting a bow, maybe new to the game, taking a shot at any moving deer. I will say this, if I am not confident I can kill the deer, cleanly, I'm not taking the shot. I don't care if the deer is standing still, walking or running to beat the devil himself.