For the moment the following Filestates are available:
The unknown state means that you are not specifying any availability data for that file. This is the default value.
===internal storage (HDD)===
You have that file on your harddrive.
===external storage (CD/DVD/...)===
You have that file on CD or DVD+-r (no video DVDs!).
You no longer have that file but want to keep it in your MyList never the less, i.e. to keep a list of stuff you've watched (otherwise just delete the file from your MyList).