Troubleshooting Audio and Video using Quicktime 6.5®
Check to see that you have QuickTime 6.5® installed on your computer. Earlier version will not play mp3 and mp4. You can get a free update for QuickTime here
Configure your Quicktime® settings . Open Quicktime. Under Quicktime Player, go to Preferences, then Quicktime Preferences. Under Plug-In , Select Play Movies Automatically. (If you are using WINDOWS, you may need to deselect htis option if your video does not play smoothly. Your player is starting before enough of the movie has been downloaded. Allow the movie to partially download, then use the play button on the Quicktime viewer to begin playing your movie.
While in QuickTime Preferences , go to MIME settings .
In the Preferences window, select Connections. and configure Quicktime for your internet connection speed
Configure your MIME settings so that Quicktime can read your files. Make sure that Streaming is checked, All components in Video are checked , all components in MPEG are checked and under MP3, MP3 audio file is checked
Select the correct movie link for your internet speed connection.
For more troubleshooting tips, visit http://www.apple.com/quicktime/products/qt/