I think I asked Marvin about that, like a year or two ago.
The answer is, yeah, they did find out who he was, but the details are highly forgettable. As in, Marvin answered my questions with some details about the guy, and they were really, really boring and forgettable. Maybe it had something to do with the "Something Awful Forums?"
Anyway, the mystery and lore that has built up around the guy, far outshines the actual story. I remember thinking that, when I got my answer. He was just some guy, who stayed over at CWC's house for a weekend and was never heard from again. I think they might have had some sort of RL connection, friend of a friend type deal, that helped set it up. They made a video or two, he disappeared and wasn't really heard from again. It's not a mystery that consumes Christorians or anything.
That's about all there is to tell, as far as I can recall.