ITER won't produce any stable power at all, so they most likely mean something like "A single run of ITER will consume about half a gram of hydrogen while having a peak output of 500MW (for a few seconds).
The current record is, like, 10 seconds and no one has broken even on input/output power...
Edit: Ah, actually the current record is less than 1 second: http://en.wikipedia.org/wiki/ITER#Background