You might want to look into a renamer like filebot or TinyMediaManager. I don’t use either one of those on a regular basis but I believe you can set those up to rename all your files with the TMDB or IMDB number automatically
If you’re thinking about doing this for your whole library you can do items in bulk very quickly, instead of looking all those numbers up and inputting them manually
Why? That’s a good question. There is a feature request about this subject
