The only thing I'll say on this matter is this, if you are going to use the LP footage of others, and it has been confirmed without a doubt that it was from that person's playthrough, then you should credit them just like you would credit any other source. Anything can be replicated for footage, and it's easier if it's a scripted event. However, if it was not and you are trying to recreate it then you'll have a hard time doing so given how in game NPCs aren't like actors and you can't put them in the same place they once were. Unless the video in question on YouTube has a Creative Commons icon on it, you have to obtain permission from the uploader to use it, as is stated in YouTube's Terms of Service. Whether people follow that or not is another story, but that's how it's supposed to be, and in any attempt at being scientific then one should always credit outside sources.
And before the chance of some people jumping me, I do credit the developers, publishers, voice actors, and composers in most if not all my LPs. I don't know who the hell Thunderf00t is, and personal I believe women do need more representation in games, but Anita is not a good person to be considered the one leading the charge due to how she supports her arguments. Not only that, but she has such a negative connotation now, that it'd be impossible to get anywhere in all honesty.