I was under the impression that no login and password were needed. That may or may not be true. I logged into my prisonplanet account, and then loaded the .wmv's up into free download manager. They all downloaded extremely fast as it is a multi-threaded downloader. You can also set up free download manager to enter a login and password (your prisonplanet.tv account) if necessary.
I don't know if you need to login or not...it looks like there is no password required.
Also, free download manager gives you the option to convert .wmv to other formats (.avi, .mp4, .mp3, .wmv, .flv, .mpg) Just right click the downloaded file and click convert.
As for linux, you should be able to play .wmv files with the correct software.