it's not just out of focus (although they've done that plenty in the past), they're focusing back and forth. so they can be focused on one girl that's in the front, and then move focus to the girl behind her, etc.
i LOVE the choreography!! it makes me get into the song more, and it's really interesting on the instrumental parts with some fast-paced moves, and the chorus is a simple but memorable dance that i can already picture the audience mimicking during performances (that'll look great with glowsticks in hand!).
also, are they saying "do it to me, baby"? lol. i hadn't noticed before.