Because of the underlying properties of docker bind mounts, it is not recommended to mount the upload/ and library/ folders as separate bind mounts if they are on the same device. For this reason, we mount the HDD or the network storage (NAS) to /usr/src/app/upload and then mount the folders we want to access under that folder.
upload/ and library/ on separate bind mounts? I think this could solve my problem if I could do it that way; I'd have 5 different bind mounts: backups, encoded-video, library, profile, thumbs and upload.