It reads the contents of the “Title” meta tag, but only from mp4/ m4v files.
Wholly different topic. There is no formal support for this in Plex, either.
You can vote on the feature request [Implemented] - Multiple Cuts Of Movie
All you can do is using workarounds Movies - Play Version - #2 by Insomnic_1
https://support.plex.tv/articles/local-files-for-trailers-and-extras/
https://support.plex.tv/articles/201018248-merge-or-split-items/
Actor data are mostly imported from TheMovieDB.org
So if you edit them over there (while abiding by the rules of this website), they will eventually be available within Plex after a few days.
