I also applaud the Range Rover's actions up until it got stuck in traffic. As HotLead said above, the moment he stopped, he was at a major disadvantage.
I would have been on the phone with the cops explaining I will defend myself as needed *hint hint... get here quick* Nothing gets marked cars moving faster than a dispatcher reporting gunshots heard over the phone.
Mobs have
zero reasoning, which is exactly why I keep a loaded AR with several magazines ready, as well as a 'go-bag.'
Most biker mobs across the nation (not all) clearly try to intimidate other drivers on the road. I pray that the driver recovers quickly, and that he invests in
proper defense 
for his family soon. I also hope that the bikers involved get criminal charges.
While I have yet to hear any evidence, the video appears to show bikes in dangerously-close proximity to the RR through no fault of his own. No options but to maintain steady speed. .. speed up, brake, move left or right, and he'll hit a biker. The only instigator I witnessed was a biker that intentionally slowed his bike in order to make contact with the front bumper of the RR, similar to what you see in insurance fraud cases, except here, it was the biker trying to be Mr tough guy show off. I have a feeling that fleeing for safety was the best option, because I bet the same assault and battery would have occurred had he remained stopped in the middle of those bikers.