The
Numberphile YouTube channel is quite famous and popular. Perhaps slightly less known and popular is the
Mathologer channel.
I find the latter to be many times of much higher quality than the former, in that the presentation is often clearer and more understandable on many of the more complicated subjects. For example, Mathologer's explanation of the
Kakeya needle problem is orders of magnitude clearer and easier to understand than the more obscure, technical and even boring explanation given in the Numberphile channel.
Sometimes it happens in the other direction, though. While Mathologer's video on
"the most irrational number" was very good, recently Numberphile posted a
video on that very same subject, and I actually found it even more illustrative and enlightening.
On that note, both argue that phi, ie. the golden ratio, is "the most irrational number". The latter video tangentially, and perhaps serendipitously, also gives an argument for what could be considered "the second most irrational number", which would be sqrt(2). (It's all about their continued fractions, and how fast they approximate the actual value.)
Indeed, it appears that if you need a "very irrational number" (that has the properties that their continued fractions have), sqrt(2) seems like an easy and good choice.