It seems that, prior to 2015, I was able to embed YouTube videos with http in the embed code. At some point since then YouTube and or Word Press decided that unless the code was https the videos would no longer appear. I assume this has something to do with security, so fine. I just had to go back and change all the http code to htttps, and now the videos are back again.
If you have visited any of those early posts and wondered where the videos were that is what happened. Feel free to revisit them and check out the videos. If you discover any missing videos post 2015, please let me know. Unfortunately, there is nothing I can do about the videos that say “No longer available.” Those have been taken down by YouTube, the artist or the manufacturer.