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I'm glad you found this topic interesting and decided to dive into it more. I think the non-transitive dice configuration they are using here is known as Efron's Dice. If you want do dive even deeper, I suggest reading about Grime's Dice and similar games for more than two players. The first link in my sources is a great place to start.

So actually I started the other way round. A few years ago I saw the video of Tokieda-sensei, then I came accross Grimes and then some older work (Martin Gardner). The idea of these dice is not that new. It dates back all the way to 1970. However, some nice variation have been made over time.

The last minute of Tokieda-sensei's video is quite nice since he couples it to probabilistic research work. So I thought it was a nice addition. :)