By creating a folder on a disk you have also created a user share. So if you make the same folder on two disks, you will have all the content in one share. Let's take your movie folders. That is a share that everything on all disks with that folder name is included. If you choose /mnt/user/movies as the host path and /movies as a container path, everything on all disks, having the movie folder, will be seen by the container in the /movie folder.