All right, here we go.
Everyone's going to contribute their "black people behaving terribly" stories and videos to confirm to each other that yes, you're entirely justified in being racist.
Before you ask, no, I do not condone any of that behavior, nor do I believe that the people involved should not be held responsible for their actions.
I will say, however, that when a society as a whole disenfranchises a group of people, that has an effect on that group of people. (Have you watched the video yet? It really makes this point clear.)
You are now dealing with the consequences of years upon years of disenfranchisement. Does this justify the behavior? Again, no. There is no justification for that kind of behavior. There is a reason why behavior like that came about, though, and it's worth considering. It's not cultural, it's not inherent in the genes, it's not a case of "Kangs gonna Kang". It's a direct consequence of generations of systemic racism.
Now, regardless of the "why" things have become the way they are, we should also consider how we want things to be. Is societal change possible? I like to think so. But I can be damn certain nothing will change as long as the attitudes that continue to perpetuate this vicious cycle refuse to adapt. Keep clutching your racism to your chest like a family heirloom and you will continue to be part of the problem.
I'm not saying go smile at a black person and everything will be sunshine and roses. I'm saying stop hating people you don't know and assuming the worst in them. We're only as civil as we choose to be.