Yes, this is the kind of skill that I find most impressive. As far as I remember the rules are fairly straightforward: only street-legal bikes (including tyres) but open to any type; run the course as quickly as possible; penalties for knocking over cones or putting foot down other than where allowed. I don't think the class distinctions have anything to do with engine capacity or type of bike - its all just the rider's skill level since the whole course is pretty much done in 1st or 2nd gear.
I also was impressed with this when I saw it first time and also don't know that it was gymkhana.
I looked for any info about Honda CB400SF (Super Four Vtec High Revo) one of the best balanced and reliable motorcycle from honda only for JDM and few more Asian Country.
Some 20 years back, I did some of those figures during my riding test (eight within 20x40 ft, turn within 20x13 ft, slow & high speed slalom, emergency stop etc...), though at much lower speed than in that video.
Nowadays, I wouldn't make those tight turns anymore, as I am too concerned to damage my own bike as my insurance doesn't cover own stupidity.
On the other side, I know I have plenty of riding experience AND my NC has the lowest point of gravity of all motorcycles I know. I recently DID a full turn within the 20ft our local roads are wide.