"Hey, look over there!"
If you present a levitation well enough, people aren't going to run
toward you--they should be running
away
If you're presenting it as a trick, specs may be inclined to try to catch you out. On the other hand, if you present it as "great googly moogly, I'm freakin' floating," you may get better reactions without as much of a risk of them rushing up to you.
I don't do this levitation (or any levitation, really) because I wear U.S. size 16 shoes, which makes the necessary "pre-levitation" footwork far too difficult. In order to take my shoes off (I wear dress shoes), I've got to sit down, untie them, and pull them off, which may be a little obvious to even the least astute spectators. As such, I can't help you with the technical aspects of the levitation. The only thing I can suggest is to keep performing it and further hone your demonstration to pick up all of the nuances that go along with performing it. If you learned from the Brad Christian video, of course you're not going to have any clue how the specs might react, as I honestly don't think the guy pays attention to his audience at all... Seems like he's just performing for his ego... But I digress.
Perform it 100 times,
then come back and honestly tell us you haven't figured it out. Experience is the best teacher!
Ciao,
Rob