I think those are good squats.
The slight "butt wink" will go away with time as you increase your flexibility and continue to learn to keep your entire lower body tight (erectors, trunk, hips, and legs). Think of really using your legs on the descent and pushing against your gut when you take that deep breath in. I cue people to "make yourself fat" when taking in their air -- it seems to help with understanding the feeling of pressing against your stomach to create a brace for your trunk. When you do this, the last piece that will inflate with the last bit of air is your chest. Some pause squats, where you MUST maintain control and tightness in order to succeed, will help you with this as well.
Also, try to point your elbows a little more downward; sending them back and and up doesn't necessarily keep your back tight. Instead, it will push your chest forward and down, creating unnecessary strain on the back, and an increased possibility that you'll round the back.
Keep up the great work!
Javier A. Sanjuan
Olympus Barbell Club
Dear God, please help me lift heavy and be awesome. Thanks. Amen.