At the top in this landing page

"Visible Only to the Uploader: The video is only visible to the uploader (when logged in). Other users (including those who are not logged in or are not the uploader) will see a message saying 'Video does not exist or access is denied' when accessing the video page or embedded link. Purpose of the Embed Code: The embed code only provides a player framework, but actual playback still requires verification of video permissions by the Bilibili server. If permissions are restricted, the embedded player will also become ineffective."