[ashlar]

The time spent is proportional to the number of items in library. Takes about 10 sec on my mid-range desktop too and 1600 movies, it's probably terrible on low power Android...
Hopefully there is a way to lazy-load the thumbs, as is done elsewhere for posters. Or the list needs to be limited, or to lazy-load the items as they come in view.

There also is a usability problem, how to efficiently select a movie out of thousands... Maybe move "similar" movies to the top of the list.

I'm not familiar with the lazy load, so need help on this. But as you mentioned, with many movies in the list, the current details view for the selection dialog is not good for usability, a simple view may be better. Or I can only list the detected same movies in the list (or use some heuristic method to detect similar movies, I doubt this will work well though), if a movie is missed in this list, user can still use the "Add version" button to choose the video file directly.

Yes, I think I mentioned a similar solution in one of my latest posts. Having the "top results" of a heuristic search (sorry if this is not the correct definition, I mean exact title plus similar titles following). And if the problem is the thumbs... I suggest we do away with thumbs. Are they really needed, after all?