There are some really good, well known magic stores in NYC. Take a couple hours and visit them.
The old blowing under the edge trick (I believe it was an aquarium originally) isn't at work here.
Neither does it have anything to do with body heat. The heat transfer from hand through air, plastic, air would not be quick enough, nor would you be able to "wiggle" it back and forth.
Magnets are a possibility, as are a few other methods.
If you really want to learn about this kind of thing visit www.themagiccafe.com
. Be warned though that secrets aren't given out willy nilly there, so be nice.