Hard to see from the cell phone capture, and from my memory. but as I was coming on top he slid my leg leg across his belly. he basically had a "half guard" on my folded knee where my knee is pinned and my ankle and shin are being compressed and pushed up, if that makes sense. basically picture a twisting and compression motion that would tear/stretch your ACL (like if you are sitting in a chair, and you cross your ankle over your opposite knee. now picture that crossed ankle being compressed in and twist up towards your chest).
At least now I know what I will be for a halloween since I am walking like a pirate!