I just skimmed the video. It seems full of information, but this video skips. It seems like either the author composed his sentences by slicing together various clips, or a few frames have been removed between some words. I tried opening the video in NewPipe as well, same problem.
I believe this is a stylistic, 'production values' choice. It used to bother me to the same degree that it seems to bother you. I suspect the content creators that do it are clipping out things like "umm" and "uhh". It might also be that some creators are better at this kind of splicing than others, which might explain why this particular example did not bother me so much.