One method for rappelling past a knot utilizing an autoblock (shunt device in this case) and a load releasable system (radium in this case). Efficient and easy with practice.
Canyoneering can be a dangerous sport and requires technical training. Do not attempt any of the ATS podcast tips without professional supervision from trained professionals.
Canyoneering course information can be seen at www.alpinets.com/canyoneering