Try this, jump up, turn and just try to land on your back. Then progress until you get it.
Basically, good advice...mind if I expand a little?
You're spinning before you even take off...so basically you're not spinning at all...just torquing your shoulders.
The key is to initiate a straight flip, and then spin. Its rotation on two different axis. Also, you should try to stay as straight as possible. Think about it like this: If you threw a pencil into a backflip, would it be easier to spin(twist) a straight pencil, or a boomerang pencil?
So here's what you should try: Work on layout/backwhips.(see included video)
You should try to WHIP back so that your body is straight through the back tuck, and you lay your head back so that you can see the ground, prior to landing(this is the fundemental to doing "layouts" off of obstacles anyways). Study videos, and study your own videos.
After you get this down, start doing layouts, and when you see the ground, coming around, try twisting your body so you land on your butt/back(as opposed to landing on your stomach if you were to land the back whip. The key is too twist AFTER you almost reach your halfway point of your rotation. And to really PULL with those arms and shoulders!
Uhhh, if I think of anything else, I'll post up! Good luck!
http://youtube.com/watch?v=ApwXdRVHju4
