Re: How to do this type of Ushiro Ukemi?
A fellow blackbelt at my dojo introduced this ukemi to us. Stand with your feet side by side. Now start to bend backwards like you want to do the limbo. Slightly twist your shoulders to the right. Now look at the mat behind you over the right shoulder. Slowly tilt your body to the back right corner, you should raise your left as you do this. Let gravity pull you down. Let the mat rolll up you right arm to the shoulder, cross over to the left shoulder then down the left arm.
To make it dynamic, don't let gravity pull you down to the back right corner. Instead push off of your right foot.. Hope this makes sense. Good luck.