looks like you're releasing the disc instead of letting it rip out of your hand. there should be enough acceleration at the last moment to make the disc feel heavy against your fingers at the rip -- a real good tug as your hand comes across your chest. it actually looks like you're decelerating during the throw, rather than accelerating.
don't curl your wrist so much at the reachback; it isn't really doing anything for you at the moment.
try to open your hips more before starting the pull -- your body should feel like it's getting twisted up -- and try to get the hit to happen in front of your body instead of off to the side. i think if you keep your elbow bent a bit longer it would help with this.
having better acceleration will help with nose-down, but i think you can also work on your grip. make sure the disc orientation is correct, in the wrist-down position:http://www.discgolfreview.com/resources ... ipit.shtml