For example, if I wanna make a "Top 5 funniest PewDiePie moments", I would obviously like to use clips from his videos. Since I would have commentary over it and kind of critiquing his videos, I'm assuming I would be in the clear. I have seen MANY videos like that from other people. In one video I found, he uses other peoples footage and also even talks about it being monetized at the beginning. I'm assuming it's okay because he has commentary and is critiquing the videos. Is there a situation where I would need to ask permission to use the clip/video? Or is it sort of a grey area?