In response to the email your son showed us, I would have to say that the answer to your question “[is] the Navidson Record real or is the whole thing made up just to write an unusual book.” I would have to say “kind of.” Certainly the Navidson Record is an invention of Danielewski, but I’d have to say that he created it for reasons other than writing a weird book, though certainly that played a role in it. One possible reading of House of Leaves is that it is a criticism of media’s ability to portray reality factually or accurately. By making up a crazy video thing he’s contributing to this theme; the fact that the Navidson record is engaging doesn’t lessen the fact that it’s fictional, much like stories that might be invented in the media.
In a different direction, by inventing the Navidson Record, he is raising questions of authorship. Even though it is credited to “Zampano” we know it is really authored by Danielewski. Who do we trust as the real author? And if there is no way to discern who is more trustworthy than the other, what does that say about the credibility of the text? I’m less sure about this reading/inturpretation but what-eves yo.
Anyway that’s what I have to say about that. Enjoy the book!