I don't know about the jet blast being able to bowl someone over, but I do remember an accident some years ago with a Ba 146 at Hatfield. The technician was in front of the aircraft when the throttles were advanced. Witnesses reported that the man rose in the air was stationary for about a second then rotated to the horizontal position and was sucked headfirst into the intake. Unlike the chap in the utube video he was killed instantly. I still have the film report of the incident.