Hi Ryan, in easy terms to somebody new to home cinema(not that I am any expert in the this field,just an enthusiast!!),a test disc helps you set up your audio and visual side of the home cinema.The DVD disc that I have can help you set up your surround sound correctly so that the signal that you hear coming from your front left/center/front right/rear left/rear right/subwoofer/speakers actually comes from the correct position in your room.
Again, the disc will also help to set up your television picture i.e.:-contrast/brightness/colour and for the more adept enthusiast,calibration and test signals to perfect the tv image to it`s optimum.I am sure there are many more experienced contributors on these forums who will be able to help you with regards info in setting up your home cinema,but, I think this DVD is worth £12.80 of anybody`s money,(experienced or novice!!)Hope this helps. Trev S-J