I'm thinking the awkward hold and reach is because he has a go pro strapped on his chest.
It does make it look like the barrel is over indexed in the screen shot, but very possibly camera angle.
To Add: How far is that back stop?
I see his sight is all the way back to the 300 I believe.
Would be interesting to see his group..... If he was shooting at a target. Looks like he's just trying to hit the stop ?