Re: multiple opponents / ending fights
Someone has to back down, or get beaten down, for it to end. I guess there is another scenario; the attackers get bored and give up the attack (which I have seen).
In the skater video, it was interesting to see the "pauses" during the first shoves, and after the go-round, there was another pause. Almost got the impression no-one there really wanted it to continue badly enough.
If you are alone against many, if you back down/try to evade, that might just be the opening the group is looking for as a sign of weakness that would trigger the attack. Conversely, if you come off too aggressive as the individual, someone in the group might think "I can't look weak in the eyes of my group, so I MUST take this guy down."
I broke up a fight in the hall of my apartment building a couple of years back (one-on-one fight). If the opportunity presents itself (me getting angry at the two fighters, and me projecting a "I might not have started this, but I WILL END IT!" attitude seemed to be the opportunity) most people will likely take an easy out from a fight...though the drunk-off-his-ass brawler will be immune to any body language let alone words.