The B-fly Guard can be a very difficult guard to pass. Especially in No-Gi Grappling. In this video Rigan Machado, one of the people responsible for the growth and spread of Brazilian Jiu Jitsu worldwide demonstrates an effective way to pass this guard.
Rigan uses a fundamental principle of droping your weight on your opponent to do the pass. What he does is put his weight on one of his opponent's hooks in order to pass the guard.
At the beginning when you are in the guard you pummel to get an underhook on the opposite side from the direction you want to go.
You also want you head to be on the side that you are going, opposite of your underhook.
