ok this one is pretty cool. the tesla coil is supercharging its metal sphere and making it very very negative. so negative that the air around it seems almost positive and the shocks jump out from the metal sphere. ok that was the charge part of this thing. now here is the cool stuff. each shock is played many times a second to get the desired sound from the coil. which means that it could be fired a few hundred times a second for a very high pitched noise. this is what plays the song. the electrons jumping off the metal heat up the air creating a mini thunder bolt. only this thunder bolt is short and in a frequency that we can hear easily. i would go into more detail about this but we havent covered sound yet and i dont really know what im talking about.
finally is the coolest part, those little neon lights at the bottom of the screen. they light up when ever the coil is firing due to the electrons just flying through the air. they enter the light and turn the light on. i thought that was pretty damn cool.
there is another video (not posted) that has almost the same thing only on a much smaller scale and you can better see the neon light effect.