Add to that, at the end of the video he said the subs were playing 30Hz and below. So no localization there. Still, it may not be the best spot, as you say.
Subwoofers, their science and placement, are a solved problem insofar as a smooth response is concerned. The answer will be always be that its most
likley that properly set up multiple subwoofers will provide a smoother response than a singe subwoofer. I don't believe there are any placement rules whatsoever that will
always result in the smoothest response in, in any room, with any listening position. I think
@juicehifi provided the correct answer above.
Here's my room with the simulator as you suggested:
Here's behind my LP at ear height.
View attachment 51706
Here's front left on the floor:
View attachment 51707
Front Left at ear height:
View attachment 51708
At least in my room and my listening position, its not a given that ear height is best vs floor.
Let's also consider what different setups might demand of a subwoofer: In a home theater with surrounds, or heights, that don't play down much below 80Hz the sub will be asked to play play much higher frequencies (a crossover not being a brick wall) and therefore be more easily noticed (localized). I can picture the chances of success with nearfield being lower in this scenario vs playing 30Hz or below with a capable set of mains, as PM said in his video. But, I won't go so far as to say don't try it and see.