“facts not in evidence (sorry its lawyerly speak I know) You do not know what happend before film...”
In the absence of facts people tend to fill in potential scenarios based on their particular biases. A good example is the Zimmeraman case where certain groups envisioned Martin being hunted, and attacked to justify their hatred of Zim. Opinions based on incomplete videos are especially susceptible to this, like the Rodney King case.
The video gives us plenty of evidence to support the illegal actions of the bikers.
Even if the SUV cut them off or cussed at them prior to the video that does not justify the bikers actions.