The axe sucks---nobody swings it like that. It should have been holding a spear or inverted sword for a downward thrust, with the point coming towards the viewer instead of away. Oh well. Practice. Practice.
He probably wouldn't have swing it straight back, he would have raised it to the side over his right shoulder, but it could be directly over his head like that on the downswing. If it was light enough, or he was strong enough, he could swing it over his head with the haft pivoting the head over his left shoulder, and then move into that position on the downswing.
Either position protects the head somewhat but leaves the belly exposed; you often swing like that using a sword two handed, but that is why samurais wore armour. He could conceivably be in that position as some point during a charge, which is what he appears to be doing, because the weapon would be moving down as he closed with his opponent. He probably can't really block, strictly speaking, but the weapon would be in the way of an opponent's swing, and the opponent would be taking a risk stepping under a moving axe blade if he tried to sneak a blow in before the orc could land his.
Regardless of how he got in that position, an overhead swing with a hafted weapon, the left hand would be further down near what would be a pommel on a sword. The right hand is about right, because you normally let it ride up the haft on the upswing, and then slide it down as you come down.