The rebuttal makes some exceptionally pedantic complaints at exceptional length (and sometimes they're technically correct! sounds like they resolved some minor confusion around the opening crawl, at least) but never seems to engage with the overall thrust of the first video. For example, the first video makes some great points about the flow of the early scenes; this rebuttal just sneers sarcastically that it's a matter of opinion and maybe it was fine the other way. I know which edit I prefer!
In fact, it misrepresents the thesis of the first video. It says the thesis was "Lucas made a rough cut and showed it to his friends; they all said it was terrible; he hired a team of editors and they saved it". The rebuttal says no, that team of editors was already in place, so the initial bad edit was already their work, not Lucas's; and every film is "saved in the edit" so it's unfair to single out Star Wars.
Now, the title of the first video is admittedly clickbait-y, but that's not actually what it claims. It says Lucas turned to his team of editors to improve the rough cut, not that he hired them at that point; and if we're being pedantic, it never claims that Star Wars was uniquely bad before editing. It's more about how Star Wars became uniquely good due to great editing.
It never even singles out Lucas for direct criticism, apart from some veiled remarks about the later "special edition" reworks. I happen to agree that those later changes were almost entirely for the worse, so possibly I'm biased...?
The ironic thing is that debunking video generally agrees with the overall point of the first video, namely that Star Wars did undergo heavy editing and was better for it. I don't think that's an unreasonable claim either because most movies do (a point also made in the first video).
Maybe if the author of the debunking video softened their tone massively it would feel more credible. Unfortunately they come across more like a bruised fanboy (despite the first video not being overly critical) rather than an impartial observer.