The bottom line is that if either of the guys had shot him, they'd be the ones going to jail and charged with either murder or attempted murder. Even if they had jumped him and just beat the crap out of him (which he deserved), they'd also go to jail for assault. It may not be right, but that's what would happen. If the guy had jumped out of the truck with a gun pointed, then you could shoot to kill...otherwise, it would be your azz going to jail and staying there a long time. In no case would deadly force in this type of situation be forgiven, as LEO would say you had the opportunity to avoid the use of deadly force. You have to be in fear for you life at the moment you pull the trigger, or you'll be somebody's bi@#ch in some prison. Does the guy deserve to get his teeth kicked in? Hell yes...but in the long run, it would be you who would suffer the most.
Hopefully, the guy's video will prevail and the jerk will get something done to him by the law.