The Butterfly Stomp is a common way of playing 1/2 Guard in no gi grappling. If your opponent has a good butterfly hook then it can be hard to pass. In the video Brent from 10th Planet Jiu Jitsu demonstrates a very nice pass.
The great thing about the 10th Planet system is how tight the techniques are. By triangling your legs in defense of the butterfly hook you gain total control of your opponents hips which prevents them from countering.
I also like the way that Brent covers his head when he turns to face Alder's legs. This will help prevent your opponent from hooking you head and sweeping backwards. There's nothing worse than a forearm in the face. Except maybe a knee in the groin ;)
