With Perian, the Swiss Army Knife for QuickTime, any OS X application that uses QuickTime can now use these additional media types:
AVI, FLV, and MKV file formats
MS-MPEG4 v1 & v2, DivX, 3ivX, H.264, FLV1, FSV1, VP6, H263I, VP3, HuffYUV, FFVHuff, MPEG1 & MPEG2 Video, Fraps, Windows Media Audio v1 & v2, Flash ADPCM, Xiph Vorbis (in Matroska), MPEG Layer II Audio
AVI support for: AAC, AC3 Audio, H.264, MPEG4, and VBR MP3
Subtitle support for SSA and SRT
N.B. Version 1.2.3 is the last version to support Mac OS X 10.4
Some Fraps videos only displayed black. [r1424] (#566)
Workaround checks for Front Row stopped being effective. [r1426] (#564)
Fixed compatibility with web video playback. [r1427, r1429, r1450] (#572)
Worked around System Preferences crashing during an update on 10.6. [r1449] (#591)
This change will take effect after this update.
Further fixes to Matroska import. [r1432, r1441, r1447] (#338, #492, #594, #601)
PPC / Intel, Mac OS X 10.4.7 or later.