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.
When we mentioned MediaTab for Windows, many of you wanted a Mac OS alternative. Invisor does the same thing and uses the same database (the MediaInfo library.) It doesn't show you the information in the Get Info window, but if you drag and drop a file or folder onto the app, you can see the media properties for each file. The General tab has basic file information, but click the extended tab to see bitrates, codecs, resolutions, number of audio and video streams, and more.
Invisor Lite is free, but the full version will set you back $2.99 in the Mac App Store and adds the ability to see info for multiple files or folders, open multiple windows, and export media information.