I think that private rooms have a code that changes every time it is created and is not unique. Another good way to create a "private" room is a friends-only room.
People create a room, and stream the desktop into pages or videos. They're not there all the time. They have to enable NSFW to be able to see them, and if they create a room it has to be NSFW. Rooms can be made private with a password or public so anyone can enter.