I am here laughing at this topic for 3 reasons:
1) What the video guy said has both a lot of what I'll call general truth; and also a bit of what I'll call specific truth... The general truth is basically just a take on the law of diminishing returns; that is, that the expectation he had was that a significant (to him) cost difference should have equated to a similarly significant performance difference. And his reality (which, after all is what really matters, our own individual perceptions and opinion) did not show that direct correlation. I feel like the umbrage being felt by some here is at least partially a result of the notion that for many in the audiophile community, having a 'law of diminishing returns' at all is anathema to the hobby itself. I mean, it's almost a Biblical level commandment that a TRUE Audiophile HAS TO hear significant differences between different equipment - and ABSOLUTELY MUST hear a huge difference if additional monies have been spent...
I'll point to a quote from mswale just 2 posts prior to mine:
"I have no idea how he can not tell a difference between the lowest cost and highest cost speaker..."
Note this quote does not mention brand, model, features, speaker size / design / driver type, etc. - anything that might directly differentiate sound quality. Only cost. (sorry, mswale, not picking on you - this just caught my attention, as your comment was actually written; instead of just something that most of the other more negative commentors were thinking while they commented - but didn't actually include in their comment...)
2) Now for the 'specific truth' part (which I am surprised I did not see anyone else point out yet). The guy compared 3 amps in a cost range of about $1000 max; and speakers with a cost range of about $800 I think was the difference between highest and lowest (?)... that's not a huge difference, IMO (and look now, I am kind of taking the opposite position of #1, LOL). And, to be fair, although he said he really didn't hear any tangible difference in the amps - he was talking about specifically when using all the same features, etc. He did say that (obviously) engaging the room correction and equalization features on the top amp made an obvious difference in sound. And again, in fairness all the speakers he tested were of a very similar type (1 or 2-way bookshelves); he didn't put the KEF s against Klipsch Jubilees (for example) and then claim not to hear any difference.
So, while I feel like what was said in the video has some general truth to it, it also needs to be said that the truthfulness of the video is specific to the rather limited range of cost... and of both the total quantity of equipment tested, and the lack of major differentiation (at least with the speakers) in terms of equipment design, etc.
Last thing that brings a chuckle is why anyone would get upset out of this guys opinion..? I don't feel like he is going to dissuade anyone from interest in this hobby; at least not anyone with serious intentions. Heck, even though I agree with some of his premise on the whole 'law of diminishing returns' thing... my own decidedly non - 'audiophile level' vintage system has been a journey of acquiring gear I desired, then evaluation of performance in my particular home environment... and yes, changing out pieces, brands or models, even things like cables (!) for what usually ended up being more expensive, more reputable, and better sounding alternatives. So, essentially the same general process as a true 'audiophile'... just (admittedly) the combination of my enjoyment level / hearing quality due to age / dedication, if you will - and desire to stay in that 'vintage' 1960s - 1970s time period... leveled out at a place where I have some very nice equipment, with what most people would consider a very nice sound... just not at that definitive true audiophile level.
I'm equally sure there are others out there whose interest level, etc. will take them all the way into the audiophile realm. And there's nothing wrong with that.