For many years, I've ripped all my DVDs, Blu-Rays, and HD-DVDs into my computer, and it's great to be able to watch any of my digital content on any of my devices whenever and wherever I want, without having to have a huge stack of discs laying somewhere accessible (I store them all in a box in my basement).
For almost as long, I've used iDentify for this purpose, but it looks like the developer behind the app gave up on the iTunes/macOS ecosystem entirely in the past year or so, and the app stopped working on macOS Sierra 10.12.
I looked around for alternatives, and found mentions of iFlicks (didn't seem as fully featured), Vidalin (no longer developed), MetaX (no longer developed?), and Subler. I tried a couple of these and didn't find them as pleasant as iDentify, but then I also found MetaZ, tagged as "Two letters better than MetaX".