Kodi and Plex can use suffixes to movie names to keep media resources assign to correct media. For example "Predator (1987) - fanart.jog" or "Predator (1987) - trailer.mkv"
Like this multiple movie can be included in same folder
I would prefer to see something like this and have it used universally. It should allow for multiple images/trailers/posters etc. though. It should always begin with the media file name, [filename (name)]. I am a little wary of structuring file names too much, but I think it would make sense in this case.
How about a structure like this:
[filename (name)].{filetype}.{number}.{extension}
Where:
[filename (name)] is the current tag value. i.e. "The Matrix (1999).mp4"
{filetype} is the type of extra data in the file. i.e. fanart, poster, trailer
{number} is just a number so you can have multiple Trailers, fanart image, Posters, etc.
{extension} = is a supported extension type for extras. i.e. All supported image formats, all supported video formats for trailers (need to stop MC from importing them though. Could be an issue.), PDF files, etc.
Some {filetype} values could have special functionality, such as "fanart" and "trailer", while others could be user defined, and wouldn't need to be hard coded to work as extras, because they are all linked to the primary media file by beginning with that file name.
The RM&CF function would need to know to rename the [filename (name)] portion of the extra files only, and move it with the primary media file. Other functions that work on the [filename (name)] tag would also need to be aware.
If this was implemented, I would love to collect trailers of some movies, and have them stored locally to show when selecting a movie to watch. Some trailers are works of art in themselves, and sometimes it is nice to compare the movie to the promise of the Trailer, without switching to a browser and the IMDB. Again, there would ideally have some functionality around the collection, correct naming, and storage of those trailer files.
If all the "Extras" files used the same functionality I would probably use it more, as it would allow for only extra files associated with a primary media file to be displayed when a list is shown.