Looks just like what we used to do, right down to the "one-step sparring hoshinsool" (self-defense) kata early in the video clip.
AFAICS, Choi is using basic pain-compliance and leverage-based jujutsu-waza, although some of it is reminiscent of some of the Chinese qin-na I learned from a student of Yang Jwing-Ming around the same time I was studying hapkido. There is some simple off-balancing that Choi does, which seems to rely largely on uke's unstable center.
Right. The only thing that makes me pause is that someone whose judgment I trusted, went to a hapkido dojang in Seoul that was allegedly in the line of direct transmission from Choi. This was around 2000. The guy reported that he "couldn't budge even a tiny female student." Looking back at that conversation, it sounded like they were doing some kind of jin training. I'm no longer in touch with the guy, or I would find out more details.
I think it's worth keeping an open mind, that perhaps this stuff is there in Korea and it's just not widely taught or advertised. I know, I know, "video or it didn't happen."
There are people out there with real skill who don't like to publicize it. It's like a black swan-- just because all the swans you've seen are white, doesn't mean that black ones do not exist.