Thats a money guillotine from top half guard. I constantly catch people in it & my trick is to make them think I'm isolating & attacking the arm then slip in the choke. And as seen, even if they roll into you once its deep enough from top you can finish from bottom half guard with lockdown almost every time. Timing the extension & squeeze power help finish that one alot too.
2nd match against john from new zealand, nice to meet u dude. i was not used to anyone being able to keep this tight with their knees and recover guard, crazy good stuff: