Okay, for some reason it took a LOOONG time for the video to load. While waiting, it just showed a blank, black box. I thought, "****! I have no defense against that!"
LOL!
So for any who can't see the video, here's what it showed, primarily. A series of videos of street fights of various kinds. One on one, multiple attackers, out-and-out melees.
Most showed fights that (IMHO) could have been avoided. In other words, pretty much willing combatants in every case. If you're a willing combatant and you could have walked away, you're not engaging in self-defense, again in my opinion. You choose to fight in the street, you get what you get. Whatever happens, it's pretty much on you.
Some of the fighters were clearly untrained. Some clearly had some experience fighting or some actual training or a combination of both. Few seemed to exhibit anything like trained discipline or more than a few basic techniques, even if they had some skills. Some were very fast, some quite slow. Many were intoxicated.
Note no kicks (at least none that I recalled seeing, I skipped around some). Very little grappling, and in such cases, the fighters tried to regain their feet rather than intentionally choosing to go to the ground.
Head shots ruled the encounters, and mostly looping hooks and overhand rights and lefts. Lots of bluffs, chest-bumping monkey dances, etc.
So...some conclusions.
1) Don't be there. Most of those locations could be avoided and should have been, IMHO.
2) If you find yourself there, leave. Most of the fighters could have walked away instead of fighting as far as I can tell.
3) If someone chest bumps you, take them out. The monkey dance has several negatives associated with it. Their friends gather, a circle forms, the chest-bumper builds up his courage with his buddies egging him on, ultimately he will fight and you can't escape. Fight on your terms, not his. He takes off his shirt, either run or kick his *** instantly. Waiting for the escalation is a sucker game.
4) Verbal exchanges are a waste of time. Don't engage verbally except to say something like "I don't want to fight you, please leave me alone." That is to establish yourself as the victim rather than the aggressor. Other than that, don't argue, disagree, or try to engage in discussion with the aggressor. He wants to fight, not talk. I guarantee he won't 'see reason' or allow himself to be talked down. He's using your words to justify his continued and escalated aggression in his own mind. Promise. It won't work, don't try.
5) Defend against the overhand right and/or sloppy hooks. That's their bread and butter. Don't let it land, counter it with your technique such that they cannot continue. Then leave, immediately.
6) Whether you have to fight or not, leave. Staying is death. You can call the cops and give your side of the story from a safe location. You have no friends in the crowd. In fact, in one of the clips, a guy just standing around watching threw in a couple head kicks to the guy who lost the fight, then walked away like nothing happened. He wasn't even part of the fight, he just decided to kick the loser for some reason. Pure pack mentality.
Getting back to what to specifically train - here's your answer. This is how street fights look most of the time. The looping head shot is the most common attack of all. Learn to defend against that and you're 80% of the way there. Learn counters that stop them before they can throw another punch. Don't get fancy. Don't go to the ground willingly (unless you're a grappler I guess, but I'm not, so that's my advice). Leave the moment you can, before or after a fight in the street.