Actually it's pretty clear what likely happened: the spellers began their spelling from stage-left, their left-hand sides based on the way they were all facing. The far-left guy probably put up an "O", and President Obama followed with an "H". The spelling comes out backwards for the camera, but is correct from the perspective of the participants.
But yeah, it's pretty funny!
(And no, the image wasn't simply reversed... check out the letters on the red shirt behind the quartet.)