A battery-powered Tesla coil. The fireball at 0:25 is the result of zapping a balloon filled with propane. At the end is a short clip of the larger coil I used as a test platform for the DRSSTC circuitry.
If you stick your hand in the plasma channel it's pretty painful, and makes pinhole-sized burns.
More details on my site: http://www.lukekambic.com/plasmahandle.html