I went to the demo, saw the button, pushed it, got confused, and finally read the description of what exactly the plugin was supposed to do, at which point I went back to the demo and noticed the little arrow.
As an unprimed user, I did not even see that arrow. However, you could always make it larger and more contrasting.
I did exactly the same thing. I can't see this being a useful plugin as it stands and I've never seen something like this in any UI either. Something like a shake or highlight would work better.
That might not be fixable. IIRC you can't directly poll for the pointer's position so the first time you have any clue is the first mouse-move (or button press) event you see once the user starts doing something after your event hooks are in place.
As an unprimed user, I did not even see that arrow. However, you could always make it larger and more contrasting.