Keep reading. The guy in the car had already been, and I hate using this word, "terrorized" by the motorcycles. One jumped in front of his car and slammed on his brakes, they all surrounded him. When they forced him to stop and tried to get him out of the car he jumped on the gas and drove off. OVER one of them. Then the fun started. He was trying to get away and finally got hung up in traffic- where they broke into his car with helmets.
The scooters were riding to an event called Hollywood Stuntz. They basically go as stupid as you can get and not lose any skin to road rash.
It's also noteworthy that a good number of the bikes were off-road dirt bikes, not street legal by any definition, and also a number of off road quads.
Calling them "bikers" is an insult.