There appears to be some space between the bar and your shins/thighs on the way up. Bar should stay in contact the whole way up. Drag it up your shins and thighs.
Also, you start head too far down, and then go too far up. Point your head at a point on the ground about 7' or so in front of you. You should never see ceiling. I've had to put a tennis ball under my chin to break myself of this same habit.