Explain Like I'm Five

They teach them to be paranoid and shoot first and ask questions later.

Don't they teach them anything before they let them out on the street.

Possibly not. If feel like that's been brought up in the news before.

Or maybe it's just a one time class or a video, and people do get complacent. Or maybe he's just a fucking dumbass and a bully. There's a clear pattern of highschool bully-style confrontation and escalation in many of the videos we're seeing, and standing there is as good a way as any to do just that.

These goons want people to be afraid of them, and act as if they believe that intimidation is a forcefield of some sort, like if they're enough of a threatening asshole that it'll mean they never get hurt.

The whole "act like a scary hardass and people will comply" strategy relies on shock and the tendency for people to freeze up and get rattled when suddenly confronted with a threat from authority or power. They want people to go all deer in the headlights when they get in their face and comply without a fight, or if you fight you're off guard and rattled and there's less of risk to them so they just get to wail on you for a while. It's gratifying for bullies when things are one-sided like that, it makes them feel powerful and righteous. In terms of getting what you want from people, it works well... up to the point that it doesn't.

After that point it's one type of catastrophe or another.