Search watched shows/movies by title or ID.
It would be so much easier if we could also filter a user/library/shows/watched call (also with movies) to search for a specific title or comma separated list of titles, to save a massive list being returned and searched when you're only looking for one title. for example, looking for 'tt0468569' in a returned dump of over 400 entries.
Assuming the activity API calls will work ok for you. If not, please provide some more use cases those don’t cover.
You can filter those by a comma separated list of movies/shows and just return the watched actions like scrobble,checkin,seen. Let me know if this works.