If you were alone or even with one buddy and you both were unarmed, what could you do to a gang? The other two didn't fare well.
Break it up? This wasn't a bar fight, it was a gang. You would be in it for the duration.
From what I saw, ,there were three punks beating up two men...I dont recall it being said that the other people in that crowd were part of that gang...nor were the people driving by in their cars part of that gang...unless I am greatly mistaken, most of that people in that crowd were not connected to either the three thugs, or the two men that got beaten up...
As has been pointed out before, all it would have taken would have been for a few people to shout for the police, and the crowd could have rushed the three thugs and held them until the police arrived...
I do realize that sometimes circumstances would prevent someone from giving assistance, because they would be putting themselves into immediate danger...but I dont know that this is the case in this situation...of course, I was not there, just saw the film of this attack...from the film, I just thought that the numbers in the crowd could have done more...
One time, long ago, my brother broke up a street fight, where three guys were beating up another guy in front of a bar...my brother, being mighty big(6'5", 280lbs), thought he would lend assistance to the one getting beaten up...other people followed his example, and the three thugs were appropriately subdued, and held until the police could arrive...
My brother got stabbed right next to his right eye with broken glass...he had to be taken immediately to the hospital, and thankfully his eye was not damaged, and he retained his sight in that right eye...very thankfully, because he was already blind in his left eye, as a result of an accident when he was a child...My mom was hysterical when this happened, and chastized him for putting himself into such danger, and coming close to being permanently blind...his reply was that he just was not thinking about that...he saw someone in dire straights, who needed help, and without even thinking, he just came to that mans aid...luckily for him, he came out of it ok...
Until I see any video differently, it just appears that the members in the crowd just did not care to help, but rather just wanted to watch..