I wasn't a fan of their audition (Bang Bang) and the other performance that they gave (Burlesque) but when they got to the modulation of this arrangement I got goosebumps all over.
That was MUCH better than their previous performances. The vocals were a little shaky at the beginning, but the key change was quite powerful. They need to decide who does the runs and when they're going to do them, because it becomes far too much when they are riffing over the top of each other.
I'm looking forward to seeing what they can do with some instruction.