I don't really know what happened here. According to the article, there was an accident in which a Range Rover hit the back tire of a motorcycle. I am assuming that this incident is what occurs within the first 30 seconds of the video.
If this is the case, then I don't know why the bikers are so pissed. Yes, the Range Rover should have been paying attention and should not have hit the bike's tire. However, I don't think any significant damage to the bike occurred. And the only reason that he hit the bike is because the assholes all surrounded his vehicle in the first place and inexplicably stopped in the middle of the highway where there was no traffic light, stop sign, yield sign, or any other reason to stop.
Maybe the Range Rover's driver made a rude gesture, honked, or did something else due to being annoyed at the fact that his vehicle was being surrounded by ~30 bikes and he couldn't move anywhere on the highway; I do see one of the riders looking into the vehicle, and even looking back at the driver as he purposefully slows down after getting in front of him.
However, just because a driver flips you off doesn't give you and your thugs the right to stop on the interstate and block his vehicle for a confrontation.
After the bikers start damaging the car, the Range Rover drives away, hitting a few bikes in the process. The bikers give chase and continue to try to block in the Range Rover. At one point, a biker manages to open the driver's door, but can't do anything before the Range Rover gets away. In the end, the driver gets fucked when he gets off the interstate and gets stuck in traffic. They break his window with a helmet and then proceed to beat him. In front of two passengers: His wife and small child. The last part of the video that you see is the window being broken.
http://www.nydailynews.com/new-york/pack-motorcyclists-chase-man-suv-attack-upper-manhattan-street-fender-bender-west-side-highway-article-1.1471585If it had been me, I would have fucked up my car, but at least 20 of those assholes would be lying on the pavement rethinking their life choices. We would have had a fun game of "Slam the Brakes and Swerve" on the interstate.