This is Christina Perri singing Bang Bang Bang, live off her Ocean Way Sessions EP.
I discovered Perri yesterday through an unlikely source - a guy from running group posted her video on his profile, prompting me to wonder if he had been hacked by someone who was insidiously posting soulful, slow break-up songs on his wall. I checked my wall but no one had posted any Christian pop songs, so I assumed my password was strong enough.
I really like her voice, and I also really like how sometimes she gets this look like, "Holy shit, there's MUSIC coming out of my FACE!" And pop culture needs more pretty girls with tattoos.