That is very frustrating to watch. The victim is just a punching bag for the guy. That doesn't require any fighting skill , just load up and throw a punch at a guy covering up. I want the victim to explode on the punk but I also know his two buddies would have joined in the fighting then.
But still, you got to fight back. Take a few more punches but at least having the satisfaction of making one good connection to that skinny ass punk.
Not one fellow passenger even yelling for them to stop is very telling. I wonder if the victim had been black would the fellow passengers do anything? Is this just another case of Kitty Genovese of NYC?