song i heard in american eagle!!

i was in american eagle the other day and i heard a song that i thought was pretty catchy but i didn't manage to hear any of the words all i know is that in the beginning of the video they have all cardboard equipment (the amp, guitar etc.) it had a pop-punk sound to it.

was the lead singer a girl? and the chorus was "that girl's like a ghost to me..."
if so it's mixi- i miss those days (ghost)