I want to point out a few things that tie the demo vid Brian posted to the current situation in South Korea.
A BBC story two years ago observed of life in ROK boot camps that
...living conditions in most barracks remain Spartan, with conscripts often sleeping packed together on the floor. The conditions are little changed from the 1970s, when South Korea was a much poorer country under military dictatorship.
Training, also keeping to military standards of a generation earlier, was, according to the report, rigorous and harsh, which dovetails with what my Korean students told me (and I don't think they've told me even half of what they went through), including long treks in their underwear through the snow during winter and severe psychological pressure from DIs attempting to weed out recruits who don't have the requisite iron. In spite of government promises to make the soldiers' human rights more of a priority, things have not improved, I gather; if anything, the steady withdrawal of US troops and the steady belligerance of the North Korean leadership have made it clear to the South Koreans that they may very well be on their own in the near future, with a reckless and hostile regime at their gates, dominated by another seemingly delusional dictator (who is likely to be convinced that his nuclear weapons development program gives him a lot more bluffing room than he had a decade ago, when it almost seemed as though a rapprochement between the ROK and the North might be in the offing). The Korean and Vietnam wars happened a long time ago to
us, but not to the Koreans themselves: there is no way for us to visualize the armaggedon-like impact of the wars on the Korean mind-set,
particularly in the military. And the treatment of recruits is correspondingly harsh; the comparison with Sparta is an apt one not just in terms of physical comfort but in terms of the brutality of their training. It takes its toll: more than 60 suicides a year amongst new recruits. Severe discipline and harsh training are the default in the ROK military and abuses are typically not investigated.
The guys you're seeing in that demo survived that treatment and demonstrated sufficient skill to be part of a demo unit for which the ROK army has 600,000 soldiers to pick and choose among. They are tough and they are anticipating combat that their national survival depends on. If they lose the next war they have to fight, they lose not just the war but their nation as well. The extreme techniques that they're practicing definitely have a combat value, not because anyone is planning to do a 360 in combat, but because, as suggested in Shesulsa' post above, agility, balance and
orientation are crucial battle skills in CQ combat and need to be trained intensely. And jumping/twisting exercises requiring you to identify and strike multiple targets in succession while carrying a heavy combat firearm strikes me as about the most intense kind of training for those fighting skills you can get.
When I raced downhill skiing, I saw a film of part of Jim Hunter's training routine. Hunter was one of the stars of the Crazy Canucks, probably the all-time best Canadian ski team, and he raced downhill mostly, where you get ridiculously fast speeds combined with serious turns on icy, sadistically steep runs. One of the ways Hunter trained was to climb
into the outside assembly on a tire on one of the huge farm machines used on his father's farm and have the driver take the machine at around 5mph or so around a field while Hunter spun around inside the tire like a shirt in a clothes dryer. The point was to habituate himself to that kind of severe rotation so that his sense of body orientation and position would become trained to the point where even after a long jump in a complete tuck, landing on a curving track at 70mph or so and maybe another one coming up in few seconds, he would still know exactly which way was up and where his various limbs were in relation tot he track. That's what you do when enough is at stake.
These guys are facing way greater hazards than Jim Hunter was, and are trying to give themselves every chance of surviving and punishing North Korean aggression. They train not just for strength and firing accuracy but for the whole package: balance, orientation, accuracy in H2H, the whole works. You can be quite sure that they know exactly what they're doing and what to do to anyone who confronts them with a bayonet or anything else.