In my experience, which is also not limited, this was a demonstration and not a 'fight', probably ripped off one of those "Learn Wing Chun at Home in 5 Easy Steps" videos.
I saw this as a "fight club" kind of fight, not a random throwdown. The crowd and fighter reactions are consistent with this kind of situation. The fact that there's a big crowd at all makes it consistent with this kind of situation. Random throwdowns don't have 15 or 20 guys cheering for various fighters.
As for your assessment of the fighters themselves, I have to disagree. In my experience (which is not limited) the "haymaker guy" reacts very much exactly how an untrained guy can be expected to react. The wing chun guy reacts very much exactly the way I'd expect someone to react with 1-2 years of training.