I think most long time forum regulars have seen that clip possibly up to half a dozen times, so it is quite well known.
Your point just seems to be: train boxing. Which is great advice in whatever context it comes.
It won't be a silver bullit against multiples though, nothing is - that's my point.
If memory serves this was quite an accomplished boxer, anyone like that is going to look great fighting some randoms.
The clip shows someone who:
was aware and controlled the distance.
understood the meaning of timing and used it
knew how to move, keep and maintain his center, making the others lose theirs.
I think SDC displays all those qualities as well, he didn't though give himself a car park to run around in and back up into.
He also didn't get to hit those guys with realistic levels of force - if he had he probably would have dropped eachone pretty quickly I guess.
This really shouldn't be turned into some style v. style bullshit though. All martial arts need to expouse a large share of similar principles per context to acheive succesful outcomes. The main difference comes down to how people train and to what level.
I would be very surprised if people here are regularly turning up to Boxing gyms or are suddenly going to.