Guard passing can be a real nightmare in jiu-jitsu. Focus on your posture and slowly working your way out - eventually they will just give you the pass if you are persistent.
I did notice at one point that you had control of his wrist and that you were able to force his wrist to the ground - consider putting all your weight on that wrist, standing, moving your weight and his over that trapped wrist and then passing it to your other hand. This chicken wings him arm behind his back, allowing you to freely reach back with your free hand and open his legs (the hand tha he needs to grab you with is trapped behind his back).
Just a thought.