There is a problem with every operating system, whether it's a Mac or a PC, where the majority of video and audio files will not play back through your system, unless you download the relevant media player. It's annoying as this means it's difficult to play Windows Media Player files on your Mac and QuickTime files on your PC, without additional software. One solution is to install an independent media player such as the VLC Media Player. The other is to install the relevant codec which will enable playback through your existing media player.31 Jul 2008