iTunes for Mac: “This movie requires QuickTime, which is not supported by this version of iTunes” error fix

You may get an error message from iTunes saying “This movie requires QuickTime, which is not supported by this version of iTunes.” This is because iTunes 10.4 or later on OS X Lion opens by default in 64-bit mode, while older media files are not compatible with 64-bit mode and can only run in 32-bit mode. To fix this, simply run iTunes in 32bit. To do this, quit iTunes, then Go > Applications, click iTunes then go to “Get info” and check the option of “Open in 32-bit mode.”