It's pressure to the Sub-Clavian Nerve. Simple enough.
Not in the least. Judging by the vacant expression of the man, he is pretending to get knocked out. Light,1 second pressure to the subclavian nerve will not do that, at least if you approach it from a western biomechanical point of view. Maybe it Works when viewed from a CAM perspective, but from a western perspective that is absolute and utter pants.
He is clearly faking being knocked Dizzy, DDLR. His eyes shut and his expression goes vacant. If you are knocked Dizzy from trap pressure, you have no business being in a martial arts class. But considering that you also defend Ryabko's no-touch KO video as being perfectly explainable and valid, I suspect that there is absolutely no point in discussing this with you. Despite being a good poster writing interesting historical articles, you have some frankly bizarre hangups about the painfully obvious pseudoscientific malarkey present in at least Ryabko's brand of Systema.
Systema students are specifically trained to relax their muscles and fluidly collapse away from physical pain as a harm reduction strategy, which does - incidentally - mimic the look of someone who is fainting, because the muscular relaxation is similar. If I wanted to fake being knocked out by Mr. Spock, though, I think I'd be inclined to continue the collapse all the way to the floor and then pretend to be unconscious, rather than immediately and repeatedly standing up again once the squeezing pressure is released.
My best guess as to why his eyes close during some of the reactions is that Ryabko's squeezing of his trap. muscles hurts, and his eyes close involuntarily due to the pain. After several painful demonstrations in quick succession, he's probably also dealing with an adrenaline rush.
It's perfectly explainable, in easily understood biomechanical and biological terms, as long as you understand what is actually being demonstrated rather than jumping to conclusions about it.
Which no-touch KO video are you talking about? In the meantime, if anyone's interested, I strongly recommend this thread I started on the General Skepticism forum back in 2009, which remains one of the most in-depth skeptical analyses of "non-contact combat" online - http://www.bullshido.net/forums/showthread.php?t=88537 .
It's a trap grab. Why would you want to fall away from that "to avoid pain?"
Systema students do similar drills in which, for example, the point of a blunt wooden or metal training knife is pressed hard into various parts of their body. The object is to train to reflexively relax and give way under circumstances that would "normally" cause tension, on the premise that tensing up causes greater resistance and thus more pain/potential for injury in a real fight.
It's a trap grab. It doesn't cause damage. Why fall away at all? You can, of course, argue that it is to avoid being grabbed, but you'd assume that the dropping motion would be combined with a turning motion so they could face their attacker.
Think about Systema training as attribute training, or like CrossFit. You're not learning techniques so much as developing skills; significantly, the ability to relax and effectively improvise under stress. Towards that, a typical Systema class consists of a whole string of radically different drills and exercises, based on accomplishing specific challenges.
Some of the simplest drills, like the one I described in the previous post and the one shown in the "Spock" video, don't look anything like "fighting"; the object is simply to train the general skill of relaxing and collapsing away from pain, assuming the worst case scenario that pain is already being inflicted. They also spend a lot of time training to avoid being grabbed in the first place, but that isn't the type of drill we're discussing at the moment.
The next progressive iteration of that type of drill might challenge the student to relax, collapse away *and then reposition*, as you suggested. The next iteration after that might involve countering during or after the reposition, or it might bring in two or more "attackers", or require that the student accomplishes the whole challenge while lying on the ground, or any one of a huge range of options.
The point is that, in each case, the student is being challenged to effectively relax and improvise their way out of danger, which is the overall goal of the training.
When did Ralph Severe quit ninjaing and started doing systema?