I am not sure. The only option to configure being able to see thumbnails is setting a file size limit larger than your video file size in Edit>Preferences. It caches all thumbnails into /home/USERNAME/.cache/thumbnails/ path, and you might have to test with a video if it parses manually, or if it picks thumbnail supplied by photo/video.
You are at the mercy of file manager (or plugin) developer who implements the frame that will be picked up, whether it be frame 1, first second, or 20% duration frame etc. Something like Directory Opus on Windows is supreme because of these niche needs. Your option in such cases might possibly be a file manager that uses external plugins like Double Commander, or Total Commander Extended addons edition via WINE.