In theory, it could be quite simple to accomplish. When you do Get Movie and TV Info for a film or TV show, it would look at the Actors/Directors list and also pull down their associated artwork, then it would follow the same method as it does for displaying TV series and season artwork:
<local cover art folder>
....Actors
........Brad Pitt.jpg
........George Clooney.jpg
........Jennifer Lawrence.jpg
....Directors
........George Lucas
........Steven Spielberg
........Stanley Kubrick
....Series
........American Horror Story.jpg
....Season
........American Horror Story - Season 1.jpg
and when you have a view using Actors/Directors, it would use the artwork from the cover art folder. Just the same as when you use Series or Season fields.
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