As described on arcattack.com:
"ArcAttack employs a unique DJ set up of their own creation (an HVDJ set up) to generate an 'electrifying' audio visual performance. The HVDJ pumps music through a PA System while two specially designed DRSSTC's (Dual-Resonant Solid State Tesla Coils) act as separate synchronized instruments."
"These high tech machines produce an electrical arc similar to a continuous lightning bolt which put out a crisply distorted square wave sound reminiscent of the early days of synthesizers. The music consists of original highly dance-able electronic compositions that sometimes incorporates themes or dub of popular songs."
Video shot at SXSW 2009 on a Canon 5D Mark II. Apologies for the poor audio. It really doesn't do it justice.