You're pathetic, that video isn't valid. You really think teachers and staff are going to type some keys like that?
Not all routers are the same configuration like that, and you'll need to be logged into an admin user account on a PC that's connected to the internet already.
If you need internet at school, use the ones where they let you. If you just want to be on MPGH while you're in class, then just die.
If you have a good reason to need the wireless internet, ask the staff at school who set it up (after you ask the nicest teachers) and don't be a little internet whore and torrent through it or watch porn.