The following is just my opinion. I say opinion because i have no experience in the matter. Frankly, i probably wouldnt get involved physically. Verbally, sure. Verbally ill stand back and yell at them, but im not going to risk god knows what going wrong because i felt like it was my problem. That might be a bit harsh, but id like to think (and though it may be accurate, its accurate at the expense of some decency) that its good self protection to protect yourself over someone you dont know.
Now, with that being said, it depends whats happening. If someones being raped in the back seat of a car, theres no way im gonna go over there and stick my head through the door. Ill call the police and try to collect as much information about the man and the car as i can. Going over there to try and be a hero might not end too well for me. Him doing something to her or me aside, what if its a ploy to get someone over there so that three guys can come running in to beat you and steal whatever you have on you worth stealing? Theres just not enough information.
Now lets say its two guys pounding each others heads in. A mutual fight. Well, that depends too. If its ego driven, like two drunks in a bar, theyd probably enjoy being held back, simply because that gives them a chance to feel like theyve shown the other persons whos boss, and someone else had to 'hold them back'.
Now lets take that video. The black guy was defending himself from what i saw. The reporter just stopped the beatdown that followed, which wasnt too bad since the guy on the receiving end just popped right back up. Furthermore, who else took the time to watch the other two people in the background? What if the guy with the baton got knocked down, then the other guy decided to come along and take out the black guy, who cant defend himself because the reporters holding him down?
Then at the end of it, the bald white guy wants to go for another round while the guy with the baton decides to leave. Meaning his friend is now outnumbered 2-1 with a bunch of reporters restraining him. Notice where he is in the end? At 1:20? Heres a question for y'all to ponder. Where did the fourth guy go? Watch the video again. Pay close attention to the fourth guy, and now try and tell me that the reporters intervention didnt put the defender in a very, very vulnerable position. At one point, his head was open and exposed less than a meter from the guys feet. Think about it. 1:22, the black guy is being 'backed off' by the reporter, STRAIGHT INTO THE FOURTH GUY.
Furthermore, you have to figure all this crap out in a second, maybe two. If you make a bad call someone else could suffer for it, not just you. Youre not the only person at risk. Your intervention wont necessarily be a good thing. That was an example of things not being too serious.
Just my opinion.