If the DVD object file that you downloaded includes a Reflectivity map, load it into the Reflectivity section and increase the Reflectivity section and it should work pretty well for you. If it doesn't include a Reflectivity map, try looking for a texture map online to use for the Reflectivity. You may find free maps online that work well for what you're trying to set up.
If you can't find any maps online, try creating the reflectivity map in Photoshop. You can probably start with creating a radial gradient with creating white streaks going from the center of the circle and going out towards the edges of the disk. If you have a DVD laying around, you can pick it up and look at how the reflections are appearing. Then draw a similar shape using black and white areas in Photoshop. The image that you draw doesn't have to be very complicated.