Your squats look pretty good, although the plates tend to obscure you at the bottom. Your bar speed and aggression under the bar are excellent. One thing I noticed is that your knees slide forward shortly after your ascent. You'll also notice this is where the bar slows down. I think this happens in some cases because you drive your butt back instead of up at the bottom and open the knee angle without moving the weight. You are moving the emphasis from the hamstrings to the quads in the middle of the ascent by letting the knees come forward and lifting the chest. Just keep driving up with the hips the whole way and do your best to keep those knees planted during the lower half of the squat. It will make you happier.