Local episode thumbail files?

[beepbot5000]

I'm trying to have custom thumbnail on a TV episode. It's named thumb.jpg in the same directory of the episode file. I had to manually do all of the metadata because the episodes are the Doctor Who 60th Anniversary Specials and they aren't in the TVDB or IMDB regular series by series episode list so they can't go in Series 14 with the new Christmas special and were being recognized as a random thing so now I have a directory just for the specials and they refuse to be scraped for so yeah I had to do it manually, and the thumbnail for The Star Beast is a random frame of a side character mid talking in their car so I wanted a custom thumbnail.  

Doctor Who (2005)
├───60th Anniversary Specials
│  │  poster.jpg
│  │
│  └───Doctor Who (2005) - The Star Beast
│          Doctor Who (2005) - The Star Beast [1080p].mkv
│          Doctor Who (2005) - The Star Beast [1080p].nfo
│          thumb.jpg
│
└───Series 14
        Doctor Who (2005) - The Church On Ruby Road [1080p].mkv
        poster.jpg