I liked the launch method - mostly internal. Apparently he used very light line to shoot with since he pulled the tag line up with the shoot line. I thought that was an extraneous step, although it may be he couldn't or thought he couldn't get the distance with the tag line. But if he could use the tag line as the shoot line that'd be better.
As for reverse engineering, obviously he's either using a spring(s)or a single latex tubing (similar tubing to the BigShot) for power. I couldn't tell from the video if there was a slot running most of the length of the tube or if what looked like a slot was actually a strong, small cord running from the top of the pole to the throw bag.
One possiblity is to anchor a strong piece of latex tubing or tension spring(s)(like a screen door spring) at the base of the 'launcher' pole (the end that attaches to the reel housing). A strong, small line would be attached to the other end of the latex tubing/spring. The string runs up inside the tubing to the other end of the pole, where it probably exits over a roller and through a small hole or slot mounted near the end of the pole. There would be a small hook to attach to the throw bag and you pull it down to the appropriate point and let 'er fly!
I think the secret with this method would be making sure the hook releases the bag.
The pole could also be slotted but that'd be a more complicated configuration. My money would go on the spring-string configuration. I may have to try that.