I learned how to rig this up a few years ago and, on the one-month countdown to my birthday, I thought I'd share this newly found "demonstration" video at Infinite Bliss, a 23 pitch 5.5-10c sport climb on Mt. Garfield. We didn't top out that day, but we sure did have a fun time rappelling down!
And yes, I do realise my Ozzie accent is terrible in this video, but two years later it really is MUCH improved! No, REALLY!
*Disclaimer: Not all harnesses come with a rear belay loop. DO NOT try this unless you are with an experienced professional and you have guaranteed that your harness has a safety rated rear belay loop.