Mac: If you have an audio or video file that will only play in a certain player or will play video with no audio, Invisor is a utility that will display all of the media information about that file so you can figure out the problem.
If you grabbed the final release of Ubuntu 10.10 this weekend, you can now fill out its codec compatibility, software updates and DVD playback powers with the Medibuntu repositories, recently updated to support the latest Ubuntu release.