The &#x27;magic&#x27; is called Content-ID and it looks for video and audio matches with content uploaded to a private (and unviewable) system by copyright holders and it takes automated action if a match is detected.<p>Theoretically any matches are reviewed by a human, but they make it quiet easy to automate the &#x27;review&#x27; process. Automated actions are typically Claim-Remove (claim content for copyright holder, remove from YouTube) for some content types (Movies, TV shows, some music) or Claim-Monetize (claim content, ad advertisements if there were not already on, and if they were already on all revenue is redirected to claimant).<p>This automated system is actually what causes the majority of &#x27;this content is not available in your country&#x27; messages, as if it gets claimed by a studio &#x2F; copyright holder who only has the rights distribute in USA and UK for example, everyone else would see that error message after it has been claimed-monetized.<p>In case anyone was curious.