A codec pack which bundles Quicktime Library components including A52, AC3, AVI, DivX, Flip4Mac, Perian, and XviD. This can fix the Quicktime error stating "Some necessary QuickTime software is missing." Installation instructions from the download site: "You're going to want to download the zip, extract it and move all of the .component files to /Library/Quicktime. The easiest way to get there, is open finder and do the following key combo: apple key + shift + g, and paste in this path: “/Library/Quicktime” and hit enter. From there, just drag the files into that folder and you'll be good to go!"