He played the game like the majority of people would play it. Follow the cut-scene, do what you're told and play the game and it will lead you to the end of the game. He did not do an RP walk and admire all the textures or amazing design choices that the game is obviously full of. He did not 100% the game either and collect everything and see everything.
Even if the youtuber didn't stop to smell the roses or rotate the trinkets, I'd still put more stock in his evidence-based impressions than those with no evidence at all claiming the game runs over twice as long.
Because we have enough reports that double that length so either that's what happened or the GAFers with the game are blatant liars/mentally challenged. Either way, I'm actually interested in the game so I'm not going to watch someone play it in its entirety before I purchase it. That defeats the purpose of a game like this.