You look like you're squatting a bit high but that might just be perspective.
A couple of things:
It looks as if your knees initiate the squat. You want to initiate by driving your hips back, not by driving your knees in front. If anything, focus on driving your knees out and hips back.
You may benefit from a slight heel lift.
You don't look particularly tight when you walk the bar out of the rack/start squatting. Pull the bar down into your back/deathgrip the bar. Take a big breath of air straight into your gut before each rep.
Your legs also jiggle about a decent amount, keep them tight between reps.
I like to pack the neck but lots of people don't/it seems to be personal preference.