My main thoughts when looking at the video, as far as the victim goes - no sense of awareness of personal space (talking on the cell phone in the midst of a physical altercation??) and of keeping good distance from an aggressor, bad decisions in playing tough guy one moment and then trying to de escalate when the Big Guy comes into the fray and then failing to run out the door (regardless of whether the woman was blocking or not) after he got the first shot. The problem was he did nothing to actually try to defend himself.
Or at least nothing even remotely effective based on the different stages of the encounter. He pretty much went automatically into victim mode.
To me this video shows a single important thing - how unprepared many of us are for dealing with "real", serious and targeted violence and how we behave (or fail to adequately adjust) when it suddenly shatters our glass house of "expected civilised social behavioural norms". It's interesting that at no point did the basic animal instinct to escape or run for one's life trigger. Imo the victim had a few opportunities to escape the altercation, well before the physical attacks started and also during the attack before he was put out on the floor. At his size the woman blocking the door could not have stopped him if he was seriously motivated and intent on running for his life. He'd have plowed right through her. This to me says something about the mental conditioning involved. Is it that when we get attacked in the "civilised" world that we are thinking "call 911" and "lawsuits" instead of basic survival first?
As far as head being down when he got the punch, he was pretty much looking at the striking hand (or at least looking in its specific direction) as the punch came. This should have triggered at least some sort of primitive reflexive/flinch defence mechanism such as raising the hands to protect the face or something. After already being accosted by the woman in a hostile manner he should have been in some sort of heightened alert state which would have allowed this, as is normal with our basic untrained responses to aggression.
As far as what I would do in that situation I think it's easy with hindsight to say anything. But having been in a very similar one I know what I'd do and have done - someone above said Shomen Ate, I was thinking along similar lines - Shomen ate carried straight thru towards the door and into the woman, letting his off balanced weight take her with him and clear the door for my escape - I'd forget joint locks, at that degree of danger I'd be snapping not subduing, but one never knows, if it presents itself, hey why not.
The good thing about big guys is that when they do go down they go down HARD, so take out the structure and pray the don't know ukemi.:
: Going to the floor could be suicide unless you are an exceptional grappler. As a pretty big guy myself I know what a little knowledge about using bodyweight can do in a ground situation, and then there is the woman there waiting to kick your brains in - not my first choice.
But to be very honest I'd not have been in the situation to begin with, since I don't let anyone get as close as that woman got with any sort of aggressive energy to start. Also, due to awareness I'd kinda sense that the guy who came storming in the door in a huff after the manager probably had something to do with the woman who was making trouble, so I'd make my escape right after the big guy entered (since the victim was also a target of the woman's rage before she tackled the manager). Judging by the aggressive and agitative energy she alone possessed I can only imagine what Big Guy would be compelled to do even if he were not so willing.
Also, what Tony S. said about the possibility of help from others being determined by how many people were there, I'd say that is about correct. The more people watching, the more people who think someone else is gonna help. Hence why when something happens and 911 needs to be called you pick someone (hopefully who has a phone) and say "YOU - call 911" else everyone else assumes that someone will do it. Weird if you ask me, but true.
Just my 2 cents.