This trick is usually performed on a bar to bar rig, although it can be caught with a catcher as follows: Swing out and make a half turn at the frontend. Over the platform, bring your legs over the bar like a pullover and hang with the bar on your waist, legs straight. Just before the peak, reach for the catcher's stick and straighten your body.
You can find out more about this trick in my books:
Thanks to Alain for providing a video for this page.