I'm a big fan of Mark and have been there since his channel started and I must admit, I never saw him play this.. I must have missed out, but in a way I'm glad I did because it let me experience it for the first time on my own without having seen any gameplay footage..
I only got stuck once and was tempted to find a playthrough until it dawned on me.. ( without giving away too much.. the red light switch in the hall ) .. I wasted about 15 minutes feeling like I hit a dead end in the game or that it glitched out on me or something until i figured it out.