caveat emptor: i am not an oly coach or even very good at it, my snatch tops out at 140-145. i'm seeing three things that all kind of bleed into one another, plus what may or may not be my imagination. first thing, i believe you're supposed to start your snatch from full tension, ie, back should be fully flexed, arms should be tight, you shouldn't be dropping down and using momentum to get the bar off the ground. the big thing is that you're not throwing your hips. when my snatch was in its incipient stages, i looked around and spent about two weeks practicing this drill:
http://www.youtube.com/watch?v=M4YQ58hMBos before going back and trying again. it'll really help throw those hips up into the pull. this works into the second thing which is that you need to drop under the bar. your ass isn't going particularly low (which i think is actually fine) and the result is that you're muscling the bar up to your catch position. this is fine at lower weights but it's not the way to train the snatch movement in particular and it'll bottleneck you down the road. really drop your ass and hips way down after you throw the hips forward and get under the bar; once the bar's above your hips you really shouldn't be pulling it, momentum should be taking it up as you get below it. The catch looks shaky and maybe a little forward, too.
basically i'd supplement heavily with rock and roll drill, snatch grip high pulls and overhead squats.