I am not concerned with either the pure audio (music) or photos - they are shared with other apps and therefore can not be moved without breaking those, Plex is secondary, although they have been working fine in PLEX.
I was playing a 720p MP4 from a directory structure that is in accordance with Plex specs (/tvshowname/season xx/files). The complete path to the show that I was watching is “/volume1/shared/video/hold/The.West.Wing/Season 06/The.West.Wing.s06e18.LaPalabra.720p.mp4”. The PLEX library points to the “hold” directory as the base of this library. This structure has been working for years through many upgrades.