Last time I checked, Youtube Tutorials we not connected to the game itself as in plays them before loading the dungeon. So my guess is that no, they are not required. They can be helpful and that's a good thing. But I've been finding it all to often that players have been expecting everyone to watch several guides and be fully experienced on fights anywhere from 3hr to a day after they are released. That's rather unacceptable that there is such a small 'grace' period for actually playing and learning the fight with the community before the negative wall of 'perfection or GTFO' is dropped.