What is missing is what happened prior to where the video starts, which would likely add a lot of context.
Without that, it is hard to judge either side. The uniformed cops might be in the wrong. The plain clothed FBI agent might have created the situation by not informing them who he actually was. Too little info, and likely the video was designed to paint a one sided picture that the editor wants.
Edit to add, the FBI agent's language and conduct is not even close to remotely professional, and if I was his supervisor, I would be having a discussion with him.
I have had guns pointed at me because uniformed guys thought I was a bad guy. I complied and got on the ground. It got settled and everyone got back to work. That guy was needs to get over himself.
I don't know anything about this video. I never saw the negro man IDed as FBI.
But if he was truly UC FBI hunting rogue cops. He played the part perfectly.
