Here is a sample unavailable video: https://www.youtube.com/watch?v=FldpMSLhjIg.  See "YouTube - video_unavailable.txt" for the page source and search for "unavailable".

Here is a video not available in my country due to copyright: https://www.youtube.com/watch?v=xmKYxwXox5g.  See "YouTube - video_blocked.txt" for the page source and search "unavailable".

See https://www.youtube.com/watch?v=8SQtDXLHfLA for a deleted video, and "YouTube - video_deleted.txt" for the source.

See https://www.youtube.com/watch?v=HOmKXhZJ3b8 for a private video, and "YouTube - video_private.txt" for the source.