Good vid. One thing he didn't elaborate on was the mental aspect of it all. Case in point - once Roger Bannister broke the 4 minute mark, which had been previously thought to be impossible, suddenly, more and more started breaking the 4 minute mark. Same in all sports. Take bodybuilding or powerlifting. Once the unthinkable 20" arm barrier was hit, more and more started to hit that mark and surpass it. Same with the 600lb bench, then 700. That mental barrier plays a large - if not the largest role of all.
Note: The 20" arm might not be the best example, as it was Leroy Colbert who was supposedly natty. Obviously with the widespread use of AAS to follow, that was more easily attainable.