I'm new to Mezzmo, trying to figure out how to set up my default thumbnails.

What I'm getting (for my videos) appears to be a frame captured from within the video file; I don't want that.

What I want is the movie/TV poster as appears on IMDB or The Movie Database. Always, by default.

(This is what Serviio does, it's what I'm used to, and it's what I prefer.)

How do I make this happen?