While I'm not a civil engineer, I do know that a concrete retaining wall at that slope would need to be hella-thick to prevent ground movement from destroying it. Such a wall would be sloped at a significant angle in order to prevent water from making the soil breach the wall by pushing out the base. The base would also be much thicker than the top of the wall because of the huge forces the ground exerts on it due to gravity. I already don't trust anything I see in video but this one just stands out as faker than usual for me.