This is a pretty rare submission, grapplers. I have not seen it used in world class BJJ and submission grappling competition in years. But, back in the day (10+ years ago) it was discussed quite a bit, especially in the RCJ Machado circles, because of Eddie Bravo, the JJ Machado Black Belt who refined it and made it famous.
I don't personally use this submission in practice, but I've had it demo'd (and attempted in free training) on me enough times to speak with authority in saying it's very effective. It was great to see it used so well last night. Even more so, it was great to hear Jung share after the fight that he learned the move from watching Eddie Bravo on YouTube. Amazing.
Check out the set up Jung used below, as demonstrated by the "Twister" himself, Eddie Bravo.