Only thing i see is that you knees move forward a bit at the bottom on the way down and then right back when you start back up. Almost like you're bouncing off of them. I've read around here (and also possibly in SS) that knees forward at the bottom is caused by loss of tension in the hamstrings though i have no personal experience w/ it or specific knowledge beyond that and don't know if that's what we're looking at here.
Other than that little knee motion they look exemplary to me.