It's completely contrary to what I've learned. But, who knows? Maybe it works because of the pressure he's using while backhoning. I do imagine though that method causes a lot of hone wear.
If I had a razor I didn't mind tearing up I'd give it a go for gits and shiggles. I've got the king stones he's using. I don't have a belt I'm willing to cut though. Nor a $350 neck knife to cut it with.
I also don't have that mystery jnat but I do have a PHIG... must be close enough. If I find something for under 5 bucks at the antique store next time i'll give it a whirl.