Stone oven

I'm sure someone here has built one of these, but I think it's so cool. Does anybody have any thoughts about the rocks exploding?
Instructables

This video is a great find! I bet his didn't crack because he's using sandstone and he is in an arid looking environment. I would love to try this but I have rock that I think will break and I am in a humid temperate environment. It all comes down to moisture trapped in that rock, if it's not bone dry it's gonna crack and some types of rock crumble easier than others when exposed to heat.
What's your rock and environment like?

Living in Maine and making my fair share of fire circles, I have used a lot of rocks. The only time I have ever had trouble was when rocks were sourced from a lake. Any rocks sourced from the land did not have any problems.