In the video we see an off duty officer who is still in uniform confront a man and the two of them engage in a fistfight. At some point the on duty police arrive and the suspect eventually is released. Are you on duty or off duty? If you are on duty then do your job. If you are off duty, how much do you get involved? It depends. In most cases the best thing you can do off duty is call the police and be a good witness.
Unless there is a serious crime in progress then you should not get too involved when you are off duty. Are you covered by workers compensation insurance if you are hurt taking enforcement action while off duty? Do you wear body armor off duty? Do you have extra ammunition, handcuffs, pepper spray and other weapons with you when you are off duty?
If you have no intention of arresting the suspect while off duty, then why are you getting involved? Do you want to write reports and go to court for off duty incidents? Will your agency back you up in the event of a civil lawsuit as a result of actions you took off duty? Generally it is best to allow on duty officers to handle incidents unless there is danger to innocent people. Be a good witness, that’s what the SGT Says.