Man that is the weakest "rubber guard" i have seen. Plus, you don't try use rubber guard to break someone down, you use it once you have someone broken down. Your arm should NEVER be stretched over his back, and he should be using his other arm to grab his ankle. He leaves his hand on the mat as Mr Zog mentioned above and while he's trying to stuff that leg I'm just clearing the neck and putting him in jiu claw/carni.
If you want something that REALLY stops rubber guard, Slick Rick has a move called the Rubber Stamp which seriously works.
I think it's on the forum.
I hate to sound degrading but this is a pretty nonsense video.