The directory commentary was added to the Bioshock games released in the Bioshock Collection. It is not immediately obvious how to actually listen to the commentary which is a bit of a pain, but once you know that the commentary is now a new collectible, it is fun to look for them. There is no trophy or achievement to find them all, but a full trophy guide for Bioshock can be found here. Thankfully you can go back and revisit past areas to collect any reels that you may have missed. In order to listen to the directory commentary in Bioshock you must locate a hidden film reel in the area that will unlock the video for you. The film reels can be a little tricky to find, when others are in plain sight.
There is a reel in each area of the game with the first one being located in the theater when you first encounter a Big Daddy. The commentary videos can be enjoyable to watch for those of us who are big fans of the game. Thankfully, game revolution have prepared a really nice guide that will show you all of the directory commentary reel locations.