It occurred to me that even if you are familiar with IT, most people have used it for levitations, but not for animations, which is a whole different ball game.
Anchors for levitations are usually done with magician's wax and no tying is needed. As Jeff discovered, tying IT (especially Kevlar IT) is a little tougher than using magician's wax!
And levis use a whole different skill set, to prevent the floating object from appearing to simply "hang" in the air, which is inartful and a dead giveaway. For animations, you need instead to learn how to guide the IT with your hands and run it through the hands, something that rarely happens with levis. Having done both, in my experience making something MOVE with IT is a different skill than making something FLOAT with IT.
Also, when something floats, most people assume (correctly!) that there is some sort of support, even if they can't actually see it. When the worm moves and it's done properly, a lot of people don't think of string or thread right off the bat. And even if they do, when they can't see a line, they dismiss that possibility and move on to magnets, static electricity, body heat, voice activation, cosmic radiation, etc.
This weekend, one lady even asked me if there was a gyroscope inside the worm. I told her I didn't think so, but that it was a good guess(!). She bought three worms for her grandchildren. SETH