Downloading iTunes extras (Error -50)

I've been trying for the last week to download the iTunes extras for one of the movies I recently bought.

every time I try to download it, it stops and gives me error -50.

what does this mean? How can I fix it? I'm currently in Costa Rica so I can't even get any support directly from Apple.

this is really frustrating me...

I've already tried resetting the cache and warnings, deleting the actual cached folder,

restarting my computer, resetting the internet connection,

nothing has worked. Have I been given some sort of corrupted file...?

thanks in advance...