Shins are not too bad here. Could they be more vertical? Probably. I would say focus more on staying tight all the way to the box and the shins will fix themselves as long as you keep sitting back the way you are. You can see here how the last 3-4 inches you are almost falling to the box then rocking to get back up. Try to stay tight on the box, sit but don’t relax then stand straight up without rocking.
Don’t beat yourself up cause these are very hard for everyone to learn.
