1. Work on that flexibility - like has been said, back is rounded in gthe start - you need to be in absolute extension - extended from sacrum to skull.
2. Squeeze it off the floor and then accelerate - that jerk is 1) counterproductive in terms of acceleration, 2) risky in tersm of injury, and 3) almost guaranteed to throw off your positioning (which it did).
3. As was said before, and was alluded to in my #2, you lead with the hips - with a static start position of that type, like John said, your hips and shoulder should rise together (back angle stays the same) until the scoop begins.
4. Weigtht is too far forward on the feet right away - a common product of leading with the hips. Aim to keep the weight centered in front of the heel.
5. Arms come in early - right as the bar passes the knees. Stretch yourself out away from the bar as you extend - no arms until you're moving down.
6. Pretty good 3rd pull - bar stays close, quick, solid turnover.
7. Jump forward to receive, and weight is on the toes - this is a result of #s 2,3,4.
Overall, a great snatch - feet move quickly and don't come up any higher than they need to; good receiving position (aside from weight distribution mentioned earlier); and a 20 lb PR is pretty huge.