the subject would have to spend ages becoming suseptible to the hypnotitst, and it would not be that quick. nor do i think it could be done on a stage where the participants are probably nervous, if it is to work the subject has to be completely relaxed, and also possible of meditation.
to conclude, the people on the stage weren't hypnotised but it is possible. its just that you have to prepare ypurself to be hypnotised and this would take like a month or sumthin.