MatPat had mentioned a couple times that towards the beginning he didn’t like to theorize on the books, because the fandom really believed the books to be in a different timeline than the games. He did do individual episodes based on a couple of the books within the past years but the first couple of books (silver eyes, twisted ones, and fourth closet) are mixed into the videos about the games.

Here’s a link to the every FnaF video ever:

He did do videos on the other books which are basically made up of short stories. From what I remember he did the first couple of books individually, as they came out, and then the last couple of books he kinda just skimmed over real quick.

Here’s the link to the first short story book: https://youtu.be/YtIVjzOHG0Y He talks about the second short story book a couple minutes into this one: https://youtu.be/5xNrAVoFT0o