I clicked the link. It opened a cryptic-looking webpage with a simple button: Apple’s familiar popup appeared: “Open in TestFlight?”

Tap your in the bottom right (or top right on older versions). Go to Settings > Try new features .

: You must be running at least iOS 16 or iPadOS 16 on your device to ensure compatibility with modern YouTube beta builds.

You will see a page that says "Become a tester for YouTube."