The first video is actually of me haha
I employed this exercise during my preparation for college football last year and I use it now because of the reduced load it places on my spine.
Anecdotally, I can say I’ve noticed great improvements in my first acceleration steps in that I achieve better extension.
Also something to note about the apparatus I use, the foot pedal allows you to use a placement to achieve a a small amount of ankle extension and in an quasi-isometric regime.
Unfortunately that machine is far to often misused and not excecuted on the manner it should be which in my mind is a highly valuable exercise.