IPA files are essentially archives that contain iOS applications. They are used to distribute apps outside of the App Store, typically through enterprise or ad-hoc distribution methods. For a regular user looking to download an app, the standard and safest method is through the App Store, where apps are vetted and updated regularly. Searching for an IPA file to download an app, especially one like YouTube, which is readily available for free on the App Store, suggests looking for alternatives outside the official channels.
: Plug your iPhone or iPad into your computer. Youtube 15.02.1 Ipa Download
Click "Start." Once the process finishes, the app will appear on your home screen. IPA files are essentially archives that contain iOS