It's a little difficult to tell from that vantage point (a little further back would be better) but it looks to me like you would do well to start with your hips back & down a little bit & use a little more leg drive off the floor. It looks like you're basically doing a SLDL until the bar gets about to the knees and then using the little bit of knee extension you have at that point. You also appear to be moving the bar around your knees on the way down instead of going straight down then bending the knees...again, hard to see for sure.
This is an example of a better angle and, though perhaps not perfect form, you can see a little more leg drive off the floor.