I am revisiting an issue I have been having for some time, but did not have useful feedback sofar. With movies and tv shows I have usually excellent results with "Get Movie & TV Shows". I also own a lot of Music DVD & Blu rays with concertos, etc. Most of these disc's do not get a lot of metadata with "Get Movie & TV Shows", let alone metadata for the chapter structure of the DVD (most videos have subdivided the piece into chapters (like movies)). "Get Movie & TV Shows" does not fill any chapter info. With Plex, however, it usually finds far more metadata for music DVD and also the chapter-info is found, which is extreme helpful when navigating a concert of opera. Is Plex using additional metadata agents which JRiver does not use (but could be using in the future).
P.S. For some discs I used MKVToolnix and did the metadata for chapters by hand. That costed way too much time.