Your files need to use the mp4/m4v container. Plex cannot read embedded meta tags from other file formats.
You could embed the name of the person either as ‘actor’ (this needs to use the iTunes-compatible format in XML format - very few metadata editors can do that).
Or you mention the name of the person in the ‘description’ meta tag.
The meta tags must be populated before you add the file into a Plex library. Otherwise you must perform the Plex Dance.
