We used to call it a "grapevine" arm-bar. The continuation if you haven't got it cinched is to let the leverage of your grapevined leg turn you to the opoposite side...you both end up in the base Japanese arm-bar position, same bodily relationships, just face down. Works great for big guys with strong benches.
That is one I've been practicing for a while. Nobody expects the foot to snake around like that. The cool thing about it is that if you can get your ankle under your uke's chin, you can pull your toes back and really lock the position tight. And then, everytime uke tries to fight the arm bar, the pressure on the neck increases and uke actually chokes himself.