Louis Theroux is the man. I've watched a small number of his documentaries, but this is definitely the craziest so far (as expected). If you have a general understanding of what goes on inside the Scientology community, this probably won't offer too much new information, but the confrontations Theroux has with current members are worth the watch. Of course, he tries to manage these confrontations with his trademark charm and faux-naivety, but when you're against people as crazy as Scientologists, it's pretty much guaranteed to be a losing battle.
When he's not busy dealing with members of the "church" that are following him and seemingly recording his every move, he enlists actors to reenact some of the events described by former members. If you've heard about "the hole," one of the highlights of the film is the reenactment of that. Let's just say the actor portraying Scientology leader David Miscavige gets VERY into his role.
This documentary really goes to show how insane this garbage organization really is. Definitely recommend this if you're looking for something to watch to enhance your negative feelings toward Scientology. It's streaming on Netflix.