Leave the platform and turn around at the front end. Swing back to the platform and then back towards the frontend. On your way back, sweep back hard and rise into a Seven position with the hips pushed towards the bar. At the peak of the swing, let go of the bar and turn towards the catcher to make the catch.
You can find out more about this trick in my books:
Thanks to Fly'n Fit for providing a video for this page.
IMAGE CREDIT: Emerald City Trapeze Arts. Lauren (flyer), David Treadwell (photo).