In my experience Plex has a serious problem with determining whether or not it's capable of playing a file back directly without converting. I regularly have to switch it to "convert automatically" to make a file play.
What can be directly played and not directly played are just lists of formats that Plex bakes into the app, and not really anything to do with mpv, right?
https://github.com/ambroisemaupate/plex-profiles/blob/master...