It's possible to rig a skin to look in the video's .actors folder for the actor image. This would allow you to keep separate images per show.
In Confluence, in DialogVideoInfo.xml, for the control with the "Actor Image" description, you can replace what's currently between the texture tags with the following:
xml:
<texture>$INFO[ListItem.Path].actors\$INFO[Container(50).ListItem.Label].jpg</texture>
That will work for movies and episodes. For tvshows, it has to be slightly different:
xml:
<texture>$INFO[ListItem.FolderPath].actors\$INFO[Container(50).ListItem.Label].jpg</texture>
In order to ensure the right path is called in the right place, you would need to duplicate the "Actor Image" and use conditional visibility. So overall it would look like this:
xml:
<control type="image">
<description>Actor image</description>
<left>210</left>
<top>480</top>
<width>160</width>
<height>160</height>
<texture>$INFO[ListItem.Path].actors\$INFO[Container(50).ListItem.Label].jpg</texture>
<aspectratio>keep</aspectratio>
<visible>Control.IsVisible(50) + [String.IsEqual(ListItem.DBTYPE,episode) | String.IsEqual(ListItem.DBTYPE,movie)]</visible>
</control>
<control type="image">
<description>Actor image</description>
<left>210</left>
<top>480</top>
<width>160</width>
<height>160</height>
<texture>$INFO[ListItem.FolderPath].actors\$INFO[Container(50).ListItem.Label].jpg</texture>
<aspectratio>keep</aspectratio>
<visible>Control.IsVisible(50) + String.IsEqual(ListItem.DBTYPE,tvshow)</visible>
</control>
(I didn't test for music videos.)
The basic concept should work in other skins but it would need to be implemented differently (i had trouble getting it to work in Estuary but i'm sure it could be figured out; i can make the images appear in new floating boxes but not part of the card deck spinner thing).
One challenge is that if you use Kodi to export to the .actors folders, it puts underscores between the actor names ("Tom_Cruise.jpg") whereas this needs the images to be named exactly like the actor name ("Tom Cruse.jpg"). So you would have to use something like Bulk Rename Utility to fix all the filenames. And of course the bigger challenge is that no scraper will pull down the images into individual folders, so you'd be on your own once you set things up this way. Just wanted to share that it could be possible with a little work.