Those of you who play a lot of video on their Macs and are running OSX 10.4.7 or later may want to pick up the latest version of Perian, which was updated earlier this afternoon.
For those of you unfamiliar with Perian, it’s a free component that, when installed, allows QuickTime Player (and other QuickTime-enabled applications) to play a wide variety of video formats that are normally unsupported, including Matroska (.mkv), Flash movies (.flv), and others.
Once you’ve downloaded the disk image from the Perian Web site, a simple double-click is all you need to install. For all the added compatibility it adds, this is a simple enough task.
For additional compatibility, you may also want to look into Flip4Mac (for Windows Media) and XiphQT (for Ogg Vorbis audio and Ogg Theora movies).