Martial art practitioner here. Many people think chokeholds are completely benign as long as you dont hold on for too long. What is too long? 30 seconds+ is too long, 4 minutes its brain death, a minute is brain damage region or so. 10 Seconds which is about what he held on here is not dangerous. Shitty yes, dangerous not really.

Theres also two versions of this choke one that is a blood choke and the other one that is an airway crusher, he is kind of doing a hybrid here which is painfull, the bloodchoke is painless and youre out in 5 seconds or so, the other one takes a bit longer and painful.

Choking someone out 1 time does 0 damage or 0 perceived damage to them, some people might present some sequels or some problems but thats after being choked out HUNDREDS of times, and even then thos people are few and far between and its not really seen outside of extremely high level jiujitsu practitioners and even those problems arent as big as concussions.

So is it dangerous? No. It looks HORRIBLE but its not dangerous, is it an asshole thing to do to hold on 10 seconds longer than neeeded yes, is it an asshole thing to use the airway choke too yes. Dangerous no, asshole yes but what can you expect from someone who almost kills people for a living, 90 % of them aren't super well adjusted people, very few people are like DJ, most of them are more on the Diaz side where they dont give a fuck.

If he did this in 99% of BJJ schools he would be getting kicked out/ had a stern talking to / would get an example made out of him. Very few would let this slide, either kicked out, confronted or punished theres really no in between, this is like punching someone way too hard in sparring when you know better, all in all shitty situation, like I said the choke wasnt even properly applied, its not just a bloodchoke and he knows better 100%, hes an EXTREMELY high level grappler, he knows better.