The reason is that the Plex Media Server is what serves (no pun intended) as the backend database and HTTP server that the client (aka the AppleTV app) connects to. Some NAS devices support a Plex Media Server plug-in, but the Apple Time Capsule does not.Why won't flex allow me to run the movies off of my time capsule? My computer HAS to be on and running Plex...iTunes does the same thing, why is Plex so good?