I think it's OK to fool around with that drill, since it's impossible to NOT swing properly from the top hand. It's similar in purpose to the "teepee drill" in David Butler's Reno vid. The teepee drill should be the first one you try, then this one.
The bungee isn't necessary. It's the bottom half of the vault (the downswing) on this drill that's important ... not the top half or the bar clearance.
If you're going to try this, remember to focus on what your trail leg is doing (or should be doing) during the downswing ... not what the hands are doing. This drill might be good in that it might teach you that you really only need to HANG ONTO THE POLE with the hands! Nothing more!
Here's a drill that does just the opposite:
http://www.youtube.com/watch?v=Hoehcs3I0gM&NR=1You will notice that in order for these wannabe stunt men to do their double-front somis, they must BLOCK OUT with their bottom arm and STOP their swing.
Kirk