(that cursed formula up there is from this other video).
Technically, you can store digital data in the internet. Send a ping to a remote computer, and in the brief time it takes for it to reply, that payload was "stored" (or rather, delayed) elsewhere. Do that often enough, and you can store substantial amounts of data by just pinging data to many computers.
That's just one of the data solutions he's come up with. The "store data in Tetris solutions" is MUCH more ridiculous and mindblowing.
My favorite part is that, instead of just staying theoretical, he does actually build and implement it.
Oh, and he casually maps the entire IPv4 range of ip adresses in a neat visualisation; not the topic of the video but really cool.
After watching 3-4 videos of this guy, he's got a lot of fun videos of complex, impractical but interesting math/computer science/data visualisation videos. Great background noise while working, too!