No, I'm pretty sure it's just a normal block of wood. It's exactly what it seems to be. The bullet shoots up into the block and stops inside. All of the kinetic energy of the bullet is transferred to the block (with some going off as sound).
I'm curious to see if other people reply with their opinions before I give my take on it. But, there's a good explanation why both cases behave like they do, and both blocks go up to the same height.
I'm saying there is "something" off... not so much that it is the block of wood.
The spin explains why it went straight up, but I don't see how they got a block of wood to spin like that... It has to go fast enough to continue the spin but not enough to keep over coming gravity. And I'd think with that speed is too low to launch the block as high as it went. I'd say 2 to 3 times greater than what i'd think. But I dunno. Maybe it's the combination of several elements together that gives an unexpected results.