Now, I love jiggleboned items. But I noticed something in the video:
The balloon strings kind of extended with movement depending on the velocity.
This could lead to several problems, one problem could be if say, a soldier shot a rocket at the Pyro's feet, and the Pyro went flying into the air, could the balloons stay there for half a second as the Pyro sails to the end of the map, resulting in a long, obnoxious string across the map?