What the actual...
I laugh at the people in the thread standing up for the guy with the lame sucker punch/tackle. Angry dude was clearly being guided to the cage to cash out and then what, taken to a back room where they explain their trespassing policy and how long he had to stay off the property? Random jerk decides to save people by creating a MMA match? From what I can tell, the biggest risk before he showed up was that people would fill up the SD cards on their phones with the "look at that crazy guy" videos. Once the situation becomes a fight, a bunch of folks could potentially get hurt. You're in a place with a ton of security, the idea that you becoming rambo is somehow helpful is dumb. Maybe there's an extremely rare circumstance where dude on the left can help out, but that entire video looked like the casino staff was professional and had things going the way they wanted.
I have a friend who trained with serious martial artists (pros, cage fighters, people like that), and he always laughed about the "justified self-defense fantasy". In his paradigm, a certain kind of person who thinks they're tough has a temptation to use the skills (real or imagined) they have to "protect" innocent people. They're looking for situations to play hero. If you told me that this guy doing the tackling was a brown belt at some mall dojo, it would add confirmation bias to my friends story.