This was not a very good video. It only briefly touched on where the -1/12 comes from (it is the difference between two ways to measure the infinite series? It doesn’t explain them well at all, just mentions the inventors, Ramaugen and Euler) and then ends with “oh and the Ramaugen proof was just the first one anyone found but there have been a bunch of way easier to understand ones since”. No explanation of what the easier ones are.
I was intrigued by your response and found this blog post about the topic https://plus.maths.org/content/infinity-or-just-112. Without watching the video itself, I guess someone tried to rip-off numberphile and made something completely incorrect.
Read the blog post and that does seem to explain the same thing but better. I don’t think the video was a rip off or straight up wrong, just not very good either.
