He got raided / investigated by a government body as well at some point (it's in one of his videos) where they went looking for nuclear materials. He had some, but it was traces and stored securely (he made his own lead/concrete container).

Anyway, Youtube - and by extension, the US government - are a bit cagey about instructions on how to make explosives (and thermite). If amateurs try to emulate it, they can injure themselves badly. I mean you only have to look at some of the "fail" compilations on youtube to see how stupid some people are.