So can anyone actually point me towards court cases that show these youtubers don't fall under fair use as a transformative work? I've seen lots of people just claim things are illegal or legal, but pretty much never based on any rulings. The fact that this only seems to ever be an issue on youtube would suggest that it is legal, but Google doesn't want to fight it. Otherwise why aren't sites like Giant Bomb or Blip shut down when they host the same kind of content.
Also, what exactly is the legal standpoint of a copyright holder taking control of content when only a portion is theirs? This is more in reference to the past where Nintendo would put ads on videos and claim the revenue. Was there any legal standing in that or was it just Google unwilling to fight it? Could the video maker have then filed a copyright claim against Nintendo since it was using their content as well?