Perian: “The swiss-army knife of QuickTime components”
- File formats: AVI, DIVX, FLV, MKV, GVI, VP6, and VFW
- Video types: MS-MPEG4 v1 & v2, DivX, 3ivx, H.264, Sorenson H.263, FLV/Sorenson Spark, FSV1, VP6, H263i, VP3, HuffYUV, FFVHuff, MPEG1 & MPEG2 Video, Fraps, Snow, NuppelVideo, Techsmith Screen Capture, DosBox Capture
The LGPL–licensed QuickTime plugin installs easily on Mac OS X 10.5 and does what it promises. FLV videos (such as those you’d sneakily download from YouTube) open just like any other QuickTime vid, and you can easily export them to other types.