Diarmuid tries to jump over Donatello's leg, but he just isn't able to get up high enough because of his size. As a result, he ends up falling backward. Even so, he seems to know that the sword swing will be coming and rolls to the side as soon as he can to avoid it. He spins around as soon as he has a chance to get to his feet and swings the staff around in an attempt to pin the sword used in the slash down.

"Did you ever manage to disarm him when he did that?"