It was twisting like a toe hold. Think "vaporizer." The vaporizer has a calf crush, but a good deal of the torque is actually on the ankle.
I watch a looooooot of youtube. I can tell you I've seen a good deal of guys crank upper body subs. More than leg locks.
As far as guys "often" cranking lower body subs hard and fast, again, I can't agree with you. I watch a lot of tourney footage, and I can only think of a handful of video where the guy cranked a toe hold too fast. Watch ADCC which has a lot of heel hook finishes. You don't see a lot of full blast heel hooking. I think Palhares is the only one who really does.
I think what gives you that impression is that guys tap late. Like I mentioned, when you get armbarred, you get near instant pain that makes you instinctively tap. Legs don't react the same way. If I apply 10% pressure on your locked elbow or shoulder, you feel pain. If I apply 10% pressure on a kneebar or toe hold, you just feel the pressure. It feels like you can let it flex a bit further. So what happens is that guys crank harder because they have a fully locked on sub, with no tap. And then the person taps too late because they didn't respect the warning signs.