Quick question about commercial use?

Please read this before replying thank you,

I read that it's "prohibited" to use to gain money, but then I read else where that the sims allows for fair use (sorry if this is a silly question feel free to answer others.) Anyways I've seen youtubers like SimgM production use the sims to advertise for other games and I believe she has ads on her videos. And a few other popular simmers do also.

Did they get permission or is this all in fair use?

I see that there's a forum I can fill out but I doubt if I get a response so I'm asking here before hand. 

I want to create machima with the sims, and monetize the videos.

😕

I also see some simmers have CC that they charge for? 

I don't get that either can we charge for sims custom content?