I can't tell for sure, since you're wearing a black t-shirt, but your horrible head position and some other indicators suggest that you're either shrugging your scapulas up toward your head in order to stabilize the bar, or you're pushing on the bar with your hands and making it slide toward your neck as you descend. This is wrong and will throw off your whole body. Scapulas together,
chest up (think about pushing your sternum out and up), and
elbows up. Your entire upper back should not shrug up, and you should not be pushing the bar with your arms.
If you fix the way you're supporting the bar, you'll not only be able to keep your head down during the lift, but get rid of a really big distraction that's keeping you from concentrating on keeping your hip active and shoving your knees out
http://startingstrength.com/resource...ad.gifproperly.