I managed to download a local copy of movies from IMDb by going into Settings --> IMDb --> Download.

Now when I go into IMDb from the main screen, I can use the top menu to Filter by year, rating, and genre, which gives me a list of movies that I can add to my Collection.

I can't figure out how to get movie posters for them (there's a setting I've enabled), or extra info for the movie apart from Name, Year, Genre.