Pick a theme that isn't too broad or shallow - has enough movies that most people will have seen at least one. Then no one has to make time to watch anything, especially if they aren't into it. People who don't generally stream won't be left out. You can have the discussion on days you feel like it. People reading may find something they hadn't considered before. So, you could pick a director (like Chris Columbus) or actor (like Alfre Woodard) or limited genre (like 70s horror movies) and people could tell about their favorite and least favorite movie that they've seen, what they think in general of the director, actor, or genre, etc.

I've never been into the book club thing because reading a book I wouldn't pick sort of feels like homework.