Can't watch the vid @ work, but it reminds me of a stalled terrain project I have sitting around.
It's a foam skull, used as a cave, with a temple inside. I was supposed to add rocks around it, plus foliage etc, but it got used in the campaign as it was at that point due to time constraints and then the incentive to finish it was gone too.
One of these days I
should finish it, because it's an awesome piece of terrain.
Just like the one you've show there! I will watch the vid once I get home and possibly get some pointers and ideas out of it too