If your using Thumbgen to generate all the data for all your movies/TV shows, then you should use .jpg’s for everything.
The .metadata’s and .jpg’s don’t coexist on the SMP/HUB and you have to use either one or the other and I always recommend using .jpgs because if you use .metathumbs and you decided to make changes it can be extremely hard to get rid of the .metathumbs because of how they are cached.
