This question has been asked too many times to count, but the answer is always the same. To play MPEG-2 in the QuickTime Player you need the MPEG-2 Playback Component for $19.99 US. It allows you to play MPEG-2 files, but not create them. With QTPro you can even save MPEG-2 files in a different format like MPEG-4. iDVD can create MPEG-2 files because it creates DVDs and DVDs are MPEG-2. MPEG-2 is a licensed technology for which there is no free standalone codec.