It gets installed when you install iTunes. If you don't want to install iTunes, you can pull out the codec installer by opening an old version of the iTunes installer in 7-zip and extracting the MSI. Here's a copy I keep around for whenever I have to do a screen recording on a new computer, it's signed by Apple so you don't have to trust me. https://www.infochunk.com/obs/AppleApplicationSupport64.msi