I looked at the 90kg work set (
http://www.youtube.com/watch?v=BY8FwPqnHBg and think part of the problem is that you are not keeping your chest up during the ascent. If you look at your upper back, it looks like it is rounding as you drive up, which will kill your hip drive. If you look at your hips and chest at as you come out of the bottom, especially in the 3rd rep, you can see that your hips rise faster than your chest.
Keep your chest up, back and midsection tight as you come up out of the hole.