A few pointers from me:
- Shoulders should be WAY IN FRONT of the bar starting from the very beginning up until the moment where your front thighs make contact with the iron.
- Try not to lift your feet off of the floor too early. This is prominent with your failed lifts.
- A part of the jumping phase is where you violently thrust and EXTEND your pelvis forward. This requires you to "open up" your hips by having your torso aligned
or arched back
with your fully-extended lower body (Knees and ankles).
You are jumping too early and are not extending enough. The top pull of a snatch should look like this:
(That's me right there. lol. Notice the synchronized extension of my torso, knees, and ankles. That's a KEY POSITION.)
Another image of this top-pull position would be Taner Sagir: http://www.google.com/imgres?imgurl=...0&tx=133&ty=54
He has a bit of an exaggerated hip extension, but what matters is you must AT LEAST have your torso aligned with your fully extended lower body OR FURTHER BACK.