I agree she def. sang live (with back up singers, they were up in the rafters)
From the way the track was layed (overlapping vocals) she can't sing it all on her own in a live performance.
I thought it was good for someone her age she has stage presence and energy, if she keeps at it she'll only get better.
I think she recorded "live vocals" earlier and they played it over her pretending to sing.. when she sings into the mic it just doesn't match up for me?