“After Snow Leopard is now officially released I was eager to see how the various changes work out in day to day use. One thing I noticed right after installing Snow Leopard was, that Quicktime X is not able to play MKV files, even if you got Perian installed.
On the Perian User Group I have found a very nice Tip how to enable Quicktime X to play MKV files again. To do so you need to download NicePlayer, mount the Image and open it once. Now you can close and delete NicePlayer and open MKV files with Quicktime X again.
My assumption why it is possible to play MKV files again with Quicktime X after launching NicePlayer once is, that NicePlayer adds the MKV Container as videofile to ~/Library/Preferences/com.apple.quicktime.plugin.preferences.plist. But since I don’t have the original file anymore I can not verify this thesis.
Anyway have fun playing MKV files with Quicktime again.”
Via [Benjamin Börngen-Schmidt]