Well, I'm still at work, so I don't have my 7D handy, but I did just look at the manual online and there is no definition of what the B/W ISO setting is. I can only remember my 40D, that when I intentionally wanted to shoot stills in mono, the camera defaulted to jpeg format, but I cannot remember if the ISO was pre-set too. I know the OP wants to shoot video in mono and now he/she has me wondering. Of course by now, they could have done it and posted the results here to clear the air.