i promise you that's not ALL done on violins.... there's guitar in there as well
they've overdubbed their fiddles and drums on an already largely complete instrumental backing track...
(hey it's what i do for a living...... )
I couldn't see any leads coming from the fiddles so were they miming?
Kit wasn't miked up either :-?

Of course they're miming, it's a music video! Another give away is that there's only one camera but several camera angles. The video editing is by Jennifer Lynn (The blonde one).
Here's the studio session for laying down the drum track, using the original S.O.A.D track as a guide.
http://www.youtube.com/watch?v=oTJa6X9fVqA&feature=channelAs for guitars...nope. That's Violins and effects pedals, and that's it. Ok, possibly an electric Cello for the lower end of things as Christine Wu does use one on some live tracks.
I've played in various bands for over 25 years. Rock, folk and crossover, and I can assure you an electric Violin with a distortion pedal is an awesome sound.
Need more proof, have a look here, in particular the 1:24 point
http://www.youtube.com/watch?v=jkQvDvtTgpk 