I suspect your grip is too narrow and that you are pushing down on the bar as you ascend. You can see your elbows dancing quite a bit as you work hard on the way up. Widen your grip and take your arms out of the lift. Don't try and bend the bar around your back. Support the weight on your shoulders. See if that helps.
Also, I suspect you need to get deeper in your squats. Narrow your stance slightly. Drive your knees out more. Profit.