These look pretty solid overall. I would squeeze your back a bit slower to start. On some of the reps, as you pull, the knees don't quite get back enough (out of the way of the bar) as the bar passes them. So get them back. Similarly on the return, yes, you tend to have too much knee bend, so the bar goes around your knees. The return to the ground is just the reverse of the pull. Unlock your knees, bend at your hip and don't let your shins angle forward (past vertical) until the bar passes your knees. You can return to the ground faster than you pull, but still want to have control, so don't add speed until you fix the knee timing.