No idea how he is doing it in half the time of others then, even in the comments on his video there is someone who says that they are only on the second boss after 6 hours played, either the build he was playing as was super OP, or the difficulty was turned down so that he could rush it, or he skipped on more side content than he thought, by his own admission, contrary to what you wrote, he didnt do "most" of the sidequests, he says in the video that he did "a lot of sidequests", so perhaps he missed more side content than he thought. Not that it hugely matters of course, he also says in his video that he thoroughly enjoyed it, so the key to take from his video I guess is that its a good game, early access of course but better to pay £24.99 now than £49.99 at release I suppose