IMO the length isnt the core problem but moreso that he structured the video in a series of segments about specific individual creators, and he doesn't really account for methods of plagiarism that he has already detailed and demonstrated at length.
Which means that since all the plagiarists do basically the same kind of plagiarism, it can very easily be very tiring to have him start going through point by point, line by line, the 3rd creator in a row to have copy pasted text then mildly edited it, rather than him going like "ok, then X repeated the same tactic as before by switching out these words" in a shorter way.
I would say that unless you are specifically interested in the two first cases(an IGN guy and AVGN) and particularly if you know about those cases already, its 100% fine to just skip those segments entirely, they dont particularly build towards the rest of the video.