I'll echo the call for BS, there's no way even a .50 will kill unless it hits, been tested time and time again and there's not even near the energy required from a close pass.
The Mythbusters test was from memory using wine glasses places within cm's of the bullets path and there wasn't even enough energy transfer to make the glasses move.
Best guess for the doe would be the difference between temporary wound cavity vs permenent, Didn't say in the video what round he used but I'd hazard a guess that it had enough zip to not even start deforming or fragment in the few inches of head it passed through leaving mostly a temporary cavity. Bet if they had taken the time to clean that skull off they would of found a near .50 cal hole from one side to the next with a few surrounding fractures.
Same goes for the "knock you on your ass" idea, can't conjure up more energy in the bullet than what the shooter is subjected to when firing it. Sure a muzzle break will save the shooter from some of the energy but that's marginal. If it doesn't knock you on your arse shooting it it won't knock a target over even if it dumps all it's energy into a solid steel plate.