It was right next to the Cambridge Museum of Technology.
http://www.cam.net.uk/home/steam/
That's a Wimshurst Generator, it creates an electrostatic charge by rubbing two Acrylic discs against eachother.
He's attempting to introduce electrons onto the two discs by creating a negative charge on the pole, just like how you rub a balloon on your jumper.
One guy, Nick..His Solid State Tesla Coil went a bit hay-wire and a streamer hit his hand. Burnt a hole right from one side of his palm to the other.
They're called High Frequency Burns. I'm not sure what would happen on a Spark Gap Tesla Coil, probably the same thing I imagine..