Not only that but 250ms is the average reaction time of a human, you don't notice an extra 5 milliseconds.
If a video is required on your website for engagement you probably shouldn't be hosting it on YouTube anyways.
Please stop repeating this sort of thing as a simple fact. Time and latency are difficult things to reason about and simple explanations sound particularly convincing when one lacks an intuitive understanding of the subject.
Perceived latency is not the same thing as "reaction time". What reaction was measured? How? From what stimulus? Your reaction time number does not support your claim that humans can't notice a 5ms difference in lag.
In any case, you are misunderstanding and misrepresenting the comment you replied to.
When you are talking about an organisation like Youtube (size, money, mercenary, malicious, etc.) and discussing metrics like this, individual milliseconds is not an unreasonable unit to use. Consider the volume of the data. Nobody is saying that if something takes 5ms longer to load that no single human being will be capable of waiting for it anymore.
Further, your 250ms is perfectly in the range of the parent comment's order of magnitude of hundreds of milliseconds.
If this is true, then why are online first person shooters noticeably worse when playing with a 250ms ping connection compared to a 5ms ping? 250ms ping is basically unplayable.
If I recall correctly. I stopped playing video games many years ago, because my college’s internet connection didn’t offer low enough latency to be able to play.
We still aren’t capable of reacting faster than about 250. However, if you have latency of 250ms then your total reaction time isn’t 250, it’s 500.
I'm nowhere close to the best player either, there's one player who recently got one of the most impressive full combos of the Metallica song One that could ever be done - they hit all notes without mistake, they got 100% perfect judgements, and they got the #1 leaderboard score, meaning that not only did they hit all notes within the 20-30ms "perfect" window, but they also "squeezed" overdrive activations within that window to activate and hit the first note as late as possible, and hit the first note after that overdrive activation would end as early as possible to still get it under the extra 2x score multiplier that overdrive brings.
The game genre also overcomes the relatively huge (in the context) human reaction time by providing you gems to read before the strikeline (or "now bar"), so that you can basically internally correct for your reaction time, similar to how people reading sheet music can perform in lockstep rhythm when everyone is skilled.
It's amazing what different forms of augmentation can do to help paper over the inherent shortcomings in our senses.
Even the experts couldn’t respond to an unpredictable stimulus in 30ms; instead, they’re choosing between (say) a 330 ms response and a 340 ms one. This is, of course, still crazy impressive.
Under certain (admittedly very specific) conditions, people can view an image, categorize it, and indicate the category with eye movements, all within 120ms. Here’s one demonstration:
https://www.sciencedirect.com/science/article/pii/S004269890...