This clip speaks for itself.
http://youtube.com/watch?v=uPkR6GXuOGs&feature=related
When do we ever learn to tidy our work area?
It doesn't really look like anything special... just a couple of tube amplifiers pumping out a considerable amount of current into a bit of wire forming a rudimentary coil.
The other "coil" connected to the light bulb merely picks up the energy from the one connected to the tubes whilst in close proximity. Sort of like an air-core transformer of sorts.