COPYRIGHTED MATERIAL
YouTube, Twitch and other services employ a robust system called Content ID that allows copyright owners to identify and to manage how their content is used on these services. For instance, every video uploaded to YouTube is scanned against the Content ID database to detect if it contains any copyrighted music or video.
Copyright owners, not YouTube, get to decide what to do with videos that contain their work. Please make sure that you pay attention to the rules.