if the bullet was a regular one, not a hallow point, the hole it made on the way out is pretty small. The brain is a vasculary organ, with a lot of small veins. A lot of brains surgery happens without “much” blood loss. It would take a few seconds for the blood to coma out, that if the hole was not blocked by the parts of the brain it self. There would be material out, of course, but for that to be perceived from that distance, the camera would have to be focused for a litlle more time. And by the way, the rifle looks like a Kalishnikov, not a Ak-47?