think there is far more to this story than the vid shows. I can see why the bikers did what they did, but excuse the sitting on the fence, can also see it from the car drivers view point too.
I personally think the bikers were causing an obstruction with their ride out, in the UK our organised events need pre planned routes and are policed and have marshals. This seemed to be very unorganised with no discipline or consideration for other road users and I imagine the car driver was getting impatient being held up by the bikes and the bikers were winding up the car drivers on purpose. None of the bikers were seriously hurt, but so many could have been killed by the actions of the driver, but if you were in a car being bullied and intimidated by 1000s of bikers when you have a 5yr old daughter and wife you are worrying about you would do what it takes to keep them safe right or wrong!