Director's Commentary in Games

Recently I have been replaying game from the Orange Box with the Director's Commentary turned on. It is really interesting to hear a developer's perspective on level design, voice acting, and how events occur. I find it fascinating to hear and see how they do little tricks to make something spectacular happen, such as the train falling at the beginning of Half Life 2: Episode2. And after listening to most of the games on the Orange Box's commentary I find myself wondering why more studios do this. Not only does it give the player more replayability but it also shows you what to look for in games, even if you would normally never notice it. So again if you never bought the Orange Box, please do because it is worth every penny