The driver definitely does not sound to be “enraged,” a bit fearful perhaps. This sort of harassment on the road seems more characteristic of bicycle groups than of motorcycles. I wonder what caused the MCers to begin to pay attention to the car. It is surely not a random thing, not on a city street.
US19 in this area is an 8 lane highway with a 55 mph speed limit. Blocking 4 lanes of southbound traffic for a bunch of idiots to do tricks would be pretty frustrating. Klosterman is a 4 lane road with a 45 mph speed limit through mostly residential areas. Sounds like dude was trying to get home at a reasonable time with his kid and had to deal with a bunch of feral yoots.