When I first clicked the link I guess in my head I was stressing the art part of ASCII art, and was expecting something other than a super-low-res version of regular video. I was imagining something more hand-crafted. Or at least more visually interesting (like that lego-ized bit in that White Stripes video, which was probably done from real video too I suppose, but surely with manual support in some way).
That said, the video-to-ASCII-art tech is actually pretty neat (and looks like more than a naive convert-to-grayscale-and-map-to-characters approach that I've seen for still images).
And so is the idea of displaying music video via live JavaScript, although that part didn't actually work for me, I had to use the YouTube link to view it.
This probably says more about me than the linked video though. It is pretty cool and creative overall.
There is a tiny part that's clearly a genuine video clip that has been manipulated (via filter or hand, maybe both) to create a kind of pixelated roughly lego-style effect. That's actually the part I was thinking of, but had forgotten that the rest of the video is basically stop-motion lego (-eseque) anyway. That's actually more aligned with what I was expecting here I think.
The author used a third party application for that.
I saw things like this in the 90s
Or this: https://github.com/keroserene/rickrollrc (Not over telnet, but same effect.)