VLC media player is a multimedia player capable of playing many audio and video formats (MPEG-1, MPEG-2, MPEG-4, DivX, mp3, ogg, ...), as well as DVD or VCD and various protocols streaming.
It can also be used as a server for streaming unicast or multicast over a broadband network.
Its main forward compared to all other readers is that it is able to read most of the videos without installing additional codec (codecs are integrated into VLC).
It is compatible with OS following:
Mac OS X 10.5 and later