People should always have a backup of all their content somewhere. Youtube had deleted over 18% of the videos I had downloaded as of Sept last year:

https://battlepenguin.com/tech/the-disappearing-videos-of-youtube/

..but the reality is people need to stop using YouTube. There use to be dozens of video sharing sites and hundreds of blogging sites. The problem is really the general population who can no longer explore the Internet and surf the web.