This is a solid-state Tesla coil. The primary runs at its resonant frequency in the 41 KHz range, and is modulated from the control unit in order to generate the tones you hear.
Amazing Video, gotta love the Mario Brothers and Tetris Theme Songs played on Tesla Coils. Must See!
Extended Edition of my video called “History of Video Games 1972-2007″. 37 new titles and new music were added.
Nicely done by applemctom @ youtube. Oh those Memories. Full List inside.