The plot thickens...
It seems Google may have taken down Blender's videos on YouTube because they wouldn't display ads for them.
https://www.blender.org/media-exposure/youtube-blocks-blender-videos-worldwide/
An update courtesy of @switchingsocial is that apparently the Blender project has started experimenting with PeerTube.
@brandon Yaaaaaaasssssss! YOUTUBE IS DOOMED