What format are your video files? mkv? As far as I know, barely any devices support mkv as it is a widely used format for pirated material. And I am guessing you downloaded all your anime for free so you really can't complain...
Not just .mkvs (which I'm in awe that no device has picked it up, as it is easily the best container for video and audio). .AVIs do not work as mentioned above as well as many kinds of .mp4s. For whatever reasons, it doesn't support certain types of mp4s. I've gotten some to work and others do not. It's quite odd.
Anywho, despite your silly comment about the downloading of anime (of which I do quite gratiously in addition the many TV series and movies I own), it still doesn't change my statement.