If you have downloaded YouTube in the past on your Apple ID, you can often avoid IPAs entirely by using the App Store's built-in legacy support. On your iOS 12 device, open the (tap your profile icon). Search for "YouTube." icon. A prompt will appear: "Download an older version of this app?"
Would you like help with for iOS 12, or finding a video downloader app that still works on iOS 12? Youtube Ipa Download Ios 12