She is good at viola, reaally good!! Makes me proud to play this instrument!!! Here are some of her videos:
Black Pearl (really good):
http://www.youtube.com/watch?v=qiI71zMqFi0
Some Nights:
http://www.youtube.com/watch?v=DRBk0pQRX-s
I knew you were trouble:
http://www.youtube.com/watch?v=mfznw9viT00
Pumped up Kicks
http://www.youtube.com/watch?v=4mH49wV5s8E
Stereo Secrets (Mash-up, this is also my ringtone!!!):
http://www.youtube.com/watch?v=401gTYT5jb4
Payphone:
http://www.youtube.com/watch?v=S8MoUig-vyw
Lucky:
http://www.youtube.com/watch?v=T7lJpbpBH5s
DJ got us falling in Love:
http://www.youtube.com/watch?v=3XCJr5lnnz8
Give me everything:
http://www.youtube.com/watch?v=UxPQVxR8_n0
Rolling in the Deep:
http://www.youtube.com/watch?v=ylAqNAOiPuc
Somebody that I used to know:
http://www.youtube.com/watch?v=rdq17MOs638&list=RD11ylAqNAOiPuc

This girl is so amazing, seriously, my idol. I would suggest you look around a bit more, I spent about an hour listening to her, she is soooo good!!! Also, Nick Kwas is a really good violin player, too, but I;m more of a viola person, although they are all fun to listen to!!
Enjoy!!!