You need to slow down. Take a deep breath into your gut before each rep, getting things tight. Which could you squat more weight with: a rigid midsection made of steel, or a malleable one of aluminum? Hey, there's a cue.. try turning your gut into steel before each rep.
After inhaling, puff your chest out like you're trying to touch your sternum to the wall. This will likely help you with your tendency to good morning the bar (notice how the bar's path moves forwards during descent, and then backwards during ascent)
The buttwink featured is troublesome and can be caused by a variety of things. But just by setting your back and breathing correctly, it will probably be fixed.
Since your current form is pretty inefficient, don't be surprised if you can manage the same workset with an additional rep when you fix everything. Post another vid here when you get the chance.
Edit: And you might want to try keeping a neutral head position.