Cool to hear that others use it. As I said before, I was never formally taught this move (that I can remember) but sorta found it on my own. I like deep half. I also like the simple side control escape of getting the underhook and turning out, pretty much the exact same motion as this mount escape only from side control and instead of hooking under the leg, you hook under the arm. Then, I started using the back door escape from S-mount and that led to me using it for normal mount. So, the motion is one I use in other areas, like deep half or side control, so it sorta came naturally and I have a really, really good success rate with it.
I use this escape a few ways. One is just like the video. They step up, I put my arm in the space, and go. I really like it coming out of a scramble when you know your opponent is going to take mount. At the last second, right before they mount I throw my arm under. Often they try to go to S-mount at which point I just go with the escape. Sometimes I will even hip up and slip my arm under their leg and just use this position to rest. Let them work on some arm attack or let them start setting up something, anything really (except the triangle, if they are setting that up, go immediately), but I will get my arm under and take a breather while they work and when I am ready, explode out and they just went from “I was 99% sure I was going to get an Americana” to “this guy is on my back now” in an instant.
Anyway, the point of this thread was that I was never shown this so I didn’t know if I was breaking some rule or doing bad jiu-jitsu. I have been told by at least one instructor not to do this escape but I have to disagree. It works great and I honestly cannot say if I have ever been caught in a triangle, or any sub, when using this escape. It makes me wonder why it isn’t taught more. Do any of you teach it or have you been taught it? Maybe its just my school?