[vemv]

That video shows poor technique, it's the arms/hands that should hover over the keyboard, in one motion.

Stretching the fingers for reaching a given key is bad, Dvorak masks this by minimizing travel, which is simply a workaround / optimization for the wrong thing that long-term will result in the same problems (simply delayed a few years).

I could use an intentionally bad keyboard layout and it wouldn't matter. Arms are designed to be moved.

[nomel]

I don't think "masking" is the right way to look at it. Regardless of exact position, all hand motion is drastically reduced, for that hand position. There are many others on YouTube that show better technique, but this was the first video in the list that showed a simultaneous top down view.