I have my doubts about certain youtubers who go through a whole Call of Duty or Medal of Honor or Battlefield game single player campaign at the highest difficulty level without dying not even once. They don't even show the screen where you choose the difficulty level before starting the campaign.
I'm not saying it is completely impossible to go through a whole campaign at the highest difficulty level continuously without dying anywhere in the game. But probably only a few people in the world are capable of making it. Certain missions are nearly impossible to win without failing not even once. You normally win those missions after many attempts.
Do you think it is likely they actually play it at easy or normal so that they can continuously go through the whole campaign without dying?