Tell him to man up and stand up, that was nothing - it's horizontal accross the head.
I've taken numerous shots dirtectly to the back of my head from a certain teammate - though at a little distance, not as close as the video
My best one was at the Reading mall game. We were playing 3 factions in a shopping centre and formed alliances every now and then. We had a stalemate at one corner with spawn points almost adjacent and battling at a shop doorway - each side watching each other through the glass then shooting it out at the door
2 of us attempted to negotiate a deal through the glass and indicated to meet at the door. So I walked straight up along the shop window, telling the team I was going in for a meeting, but kept ducked down and gun in hand
As I stepped through the doorway the guy at the door had been watching me come down and shot directly into the top of my head
My fellow negotiator then informed me 'slow down, I haven't told them not to shoot you yet!'
Later on people had a mix of concern and entertainment at the blood on my head
However paintballs to the top of my head hurt less then when i cracked a hole in my skull as a child. I still have the dip in my head