PS: Forgot to mention that in regards to your original question, using matte materials also allows you to alpha out the shadows with your render, so they can be composited into the video perfectly in post. No need for faking shadows in CG compositing, and no need for green or blue screen techniques unless you have to put a real actor against a CG background. But again, it requires the use of more high end software. Hope this helps. Otherwise, some of the suggestions already mentioned are good too.