I think people misunderstand this and that you explained it well. It wasn’t a court that struck down the video, it was YouTube. I’m not sure though what American law has to say about monolithic platforms like YouTube and hosting public domain content.
To add to the problem, social security was never meant to be an national ID number. It was just really useful for a whole lot of things. However, numbers are handed out sequentially, not randomly. So take your SIN and add or subtract one from it and that is another person’s SIN. Knowing just a few simple things about a person can reveal most if not their entire SIN.