voeg posters/achtergronden van tvdb toe!

The backdrop part already exists: open a show or movie, tap the "..." menu at the top, then "Choose the backdrop" ("Choose the poster" is right above it). It opens the full gallery we hold for that title, and your pick only changes your own view. If you went looking and missed it, tell us where you looked. TheTVDB artwork stays on the table. If you hit a title where nothing in our gallery worked, name it: that is the fastest way for us to see the gap.