Have only watched very few fragments of the video itself, because I don't feel like sitting through all that.
I personally agree to an extent; Final Fantasy XV is disappointing as fuck, but it's not a bad game. Enjoyable, but feeling the immense wasted potential that lies within (and no, Royal Edition doesn't really alter things enough to make a substantial difference, although it gives you some extra nice bonus like a decent final dungeon for a change). Half-baked ideas, questionable storytelling, questionable progression, and a very simple combat that becomes serviceable enough not to be boring but always lets you wanting just a tiny bit more of strategizing. So in essence, they could have done so much more with it than what they ended up doing.
I know this sounds repetitive at this point, but FFXV did need one more year of polishing at the very least. At least to iron out certain elements that would later need to be corrected through other means. On a side note, all the bullshit they've added to the game makes it even more disappointing than in vanilla in certain moments (timed-exclusive content for singleplayer games? Excuse me what the fuck?), so I'm not sure what Square-Enix was thinking here.
Overall, I'd recommend, just don't expect anything fantastic and be sure to tame your expectations with the "what could have been". Final Fantasy X and XIII were vastly, vastly superior to this game, though I'd put XV above XII.
