Hey Adee, just saw this and no one commented on your FS/OHS videos so I will.
FS looks like you grinded it out. Just below 1/4 squat level on the up/concentric phase, you start pushing your hips back.
In the OHS, things happen somewhat similar. Your butt tucks under at the bottom of the OHS though. I didn't see this in your FS. This is probably what also causes you to go forward on the ascent of the OHS.