In reply to colin8ll:
I never get the 'it's easier to escape the system' argument. In 25 years of climbing I've had to do it twice - none of these in a professional context.
My main concern with the fixation on easy ways to get out of the system is they forget about all the judgement calls/decisions we should be making to avoid situations where escaping the system becomes a reality.
Re your set-up the one thing you have in there that is potentially dangerous is the belay plate clipped to the Alpine butterfly. It's easy to have the alpine butterfly such that your belay plate is effectively behind you. This means potentially the breaking rope cannot be brought back to behind the plate hence you reduce amount of breaking force you can potentially exert. Now you run the risk of dropping your second.
Another point is it seems such a pointless faff to set-up. I'm keener to spend my time climbing (clip/clip) than rummaging around with lot's of knots at the top. FWIW it is possible to clip into multi-point anchors just using the rope and a couple of krabs way quicker plus once you learn hot to escape the system it's pretty quick to do. The main point in escaping the system is working to what you plan to do next not just get off the rope.
As others have pointed out this method has been around in various shapes or forms for a lot of years. Not a method I am keen myself for the main reason outlined above - the position of the belay plate and the potential for having the plate behind you and therefore reduced ability to bring the rope behind the plate to brake.