:lol: u will have to speak nicely to the IT people at ure school to remove the filter on the schools firewall. they should be able to apply an access list which will give u access to mp3's, movies and stuff, whilst still blocking access to everyone else, i'e - the kids.
i'm unaware of anything which you could use to by pass it, the It staff would find out i'm sure anyway, so approach them with a smile and see what they can do for you.
generally mp3's and movies are banned within schools due to the misuse it can bring from students (and sometimes staff).
good luck!
