Btw there is good old faq article about leaf trimming.
Also the grow style that this guy is using, well I’ve got few objections. But again it is not correct to criticize it from seeing single 17 minutes video 
so take this just as a rant. If he want light to go to lower buds, why is he vegetating plants so long. With plants so big I can’t be surprised that they bend over and need to be leaf stripped and supported by screen… But maybe it’s the strain. But I’d say that lower buds still won’t get proper light levels (due to limited light penetration).
In my eyes yield limits lie more in strain (and adjusting grow style to it) and filling the canopy (making 100% use of the light). And in this video there are clearly some empty spaces.
It would be interesting of course to see test side-by-side. Very interesting topic, thanks for pointing to this!
Actually he said that the video is repost of something 1 year old that people requested.