I doubt this is how most people's eyes actually scan a visual field. I expect there's a lot more randomness going on subconsciously, and that face-like features cause a higher subconscious dwell time.
had to click on something quickly...but that's not how Youtube works.
I think for most people it is. Scroll scroll scroll tap, all within a few seconds.
When you're only presented with a tiny bit of information, it doesn't take long to evaluate a decision. A few seconds is a long time. No one, at least to my knowledge, is opening youtube and clicking on the first thing they see in milliseconds. Hell, just variation in page loading time probably has a bigger effect on what we see first. Critically though, there's no deadline - even if you see something you want to watch quickly, you don't have to click on something if you don't see something you want to watch. Without time pressure, there's no need to make an impulsive click.
Instead you are presented with a small number of options and given unlimited time to choose, and the consequence of choosing a bad video is several minutes of wasted time. I presume most people are asking themselves "do I want to watch this" and deciding "yes, this video looks interesting/entertaining/etc." Maybe if the effect were small, like 1-2% I could believe its just a slight nudge due to psychological hacking, but the reported differences in the tens of percent and the extreme importance that seems to be placed by the algorithm indicates this is a major factor in peoples' decision making process.