your decent looks great, especially breaking at the hips and sinking them properly, the problem arises when your begin your ascent. your knees start to shift forward which could cause some problems when you get closer to maximal weight.
your hips want to pop off of the bench. make sure they stay tight or you could get a red or two.
take a huge breath to fully fill up your lungs while standing to maximize your core tightness against the belt, then grab the bar and pull, all in one breath. this will also keep you from staying down at the bar for too long.
i'm just nitpicking, but the rest looks good.
in between individual attempts, sit in a chair. some guys will stand and walk around, but you should sit to maximize your energy. between lifts, stay hydrated (stay away from gatorade for the first half of the day, glucose) and keep eating food low on the glycemic index (i like clif bars).
"Strength does not come from winning. Your struggles develop your strengths. When you go through hardships and decide not to surrender, that is strength." - Arnold
"To give anything less than your best is to sacrifice the gift." - Steve Prefontaine