Very similar to a layout, but with legs apart. Swing out and back to the platform. Lift your legs in front of you and hold them at 90 degrees. Swing down into the centre and as you reach the poles (centre of the swing) beat back as hard as you can with your legs. As you move up towards the peak at the frontend you split your legs and drive the leading leg upwards and over your head, letting the other leg trail behind. At the peak let go and tip your head back to catch.
You can find out more about this trick in my books:
Thank to Nicolina for letting us know about this trick and providing the video.