A beginner "Rocket Stove" with 4 cinder blocks

So I saw this guy on youtube claiming to make a rocket stove with just 4 cinder blocks. I wanted to see if it actually worked myself, and its great! This is a good little post-apocalyptic cook stove, or just a super cheap introduction to seeing some rocket stove concepts in action.

I might play around with adding more blocks to make a J tube.

His video-



My attempt-