I think the idea of this is to give you an idea of how they do sound. What really to me is a waste of time is to have a reviewer talk endlessly about his impressions of what he heard without a demonstration. You should be able to get an idea of maybe how they do sound because you are familiar with how your speakers present the sound that you have been listening to on the youtube video. Otherwise they are just moving air and wasting time to me.
Why on earth?
Answer me this: On You-Tube, there are endless of reviews, comparisons, and demos of equipment played in the creators room, recorded by a mic and published as if we could hear anything relevant considering we are listening to OUR stereo! Some of these have high play counts. Does anyone think they could hear differences in an amp or DAC picked up by some unknown mic, A2D, post processing and played back on their HT? Are we really that stupid?