I found this video really interesting. It's the same general trend in skills transfer/online education we've seen in other domains, but in this case applied to fighting- something deeply physical and high-risk
A couple takeways for me:
First of all, we're really still learning how to use the medium. Memories of grainy VHS training videos and stiff attemps to recreate in-person classrooms sell things short- we're still learning how to use video to teach
Second, as Icy Mike notes, this dude is highly, highly nontypical. He's athletic, mature, and very smart. Most people won't be able to learn this well.
(seriously, don't learn to fight on YouTube. unless you dislike me, in which case, uh, please do)
I wonder to what extent this creates more winner-take-all dynamics, where people with the necessary cognitive/skill prerequisites are massively enhanced, while those without get left behind
Finally, as a general rule, the baseline standard for more or less every skill should rise. The internet can't confer deep mastery, but it can get you the 80/20 fundamentals that historically most people just couldn't access
This is the basic concept @SamoBurja flagged a couple of years back in this video: https://www.youtube.com/watch?v=v5iu8wLw_Ws
high-bandwidth audiovisual communication allows you to communicate a ton of tacit details that an expert may not be able to convey