Warning- wall of text!
Upstream, you are absolutely right I have been screwed over by "the system" in my divorce. In fact, very few years ago I would have been making arguments against DJ. I have a first hand education on how the system actually works and men are at a huge disadvantage. After all modern feminist thought says that we are all violent prone batterers and the system is stacked against us. Women today have a free pass to make all sorts of allegations from violence, rape, domestic abuse, terroristic threats, harassment and a laundry list more of actions they can use to prosecute mostly men. Even if the man is entirely innocent and later is proven so, his life has been disrupted, he may have lost employment just based on the allegations, He will likely be out thousands of dollars in fines and fees, even if he is proven innocent. Once it gets out that he has only been accused of something, it is very hard to shake that label. If the woman makes it up and later it is proven she made it up, there will likely be no consequences at all to her. I could post hundreds of articles supporting the above statement. So yes the system is absolutely stacked against men for no good reason.
Now focusing on the DJ video, if he went up and cold cocked her then yes he deserves everything he is going to get. If she just mouthed off to him and then he hit her same, but that is not what happened even without the audio it is clear she raised her fist at him first. DJ then tries to restrain the hand that is in a very aggressive postion. In fact, one of the big arguments with the ray rice situation was that he did not try to restrain her before he struck her. Now we have this situation where DJ is restraining her threatening position and he is still getting crap. The woman then throws a punch which connected with his cheek/chin area. Despite Kinghighs assessment that the punch "wouldn't hurt a fly", I saw on the video it connected. Only then did DJ strike back. That woman in the video made the aggressive moves first on all accounts. She raised her fist as though she were going to strike DJ, She then did strike DJ first with her other hand. He responded. Unfortunately only one of them is going to pay a heavy price and that is the injustice of this whole episode.
Some people are equal, except some are more equal than others.