YouTube has implemented a bot detection system that requires users to sign in before accessing certain content. When attempting to view a video, users may encounter a prompt asking them to verify that they are not a bot by signing into their Google account.
The verification step is designed to protect the community from automated abuse. According to YouTube's support documentation, this measure helps ensure that only legitimate users can access the platform's content.
The page states: "Sign in to confirm you’re not a bot. This helps protect our community."
Users who are not signed in will see a "Sign in" button that redirects them to the Google Accounts login page. Once authenticated, they can proceed to watch the video.