I made that gif out of screenshots from the Mike DiFrischa video (TMZ). If they didn’t manipulate the footage then it’s true fact. Shell ejection at the exact moment of the first shot.
I assume for the first 3 shots he leand a little bit over the roof ridge and than moved back slightly to release shot 4-8. That might explain why 3 casings on the south and 5 on the north side of the roof.