The DivX Codec is very popular now due to its ability to compress lengthy video segments into small sizes while maintaining high audiovisual effects. You need install the third party plugin like Perian to make your QuickTime Player support the DivX. But it will not play some of the unique codecs like DivX.
The included QuickTime Player on Mac OS X is a very good one. Free Mac DivX Player - Play DivX on Mac Directly
