I hope I never have to use this. Knowing myself, I'd typo the knot and fall to my death.

This is how it’s taught in intro mountaineering courses. In the real world experienced alpinists carry a lightweight ascender, like a Micro Traction or similar, that can also be used for other tasks like hauling or fall protection for simul-leading.

Is that essentially a one way rachet? All you need to climb easily is prevention of regress and maybe some mechanical advantage, right?

It is a bit more complex. Climbing means falling. The 'ratchet' needs to work under shock loads. And wet/ice ropes radically change the friction numbers. There is a reason why climbers, experienced ones, know and use a great many different tricks for accending and decending ropes. A "big wall" climber can make a belay device out of almost anything, or even nothing.

like your hip!

“The leader must not fall.”

Aid climbing: https://en.wikipedia.org/wiki/Aid_climbing It's using techniques like that to go up rock walls instead of free climbing the rock holds.

Yes

I see. I tried to watch one video but they spent most of the time explaining how to create the rope/knots. I had assumed you eventually resorted to your arm strength to ratchet up the line. It does look like standing to ascend.

The overdubbing in this video is creepy, like these auto-generated voiceover videos. Why show peoples faces over completely different narration?

...because they didn't narrate in English?

Subtitles are a thing