Crossposting from Ed Calderon's site for the video:
http://edpoint.tumblr.com/post/13408...being-armed-is
Worth a watch - please note the soldier being ambushed is carrying gear and a rifle, and initially cannot get to it. May never have if a bystander had not helped. The rifle is a long weapon and hard to bring to bear at such close quarters if not already mounted, or if the muzzle has been averted.
It appears that the soldier may access his own short blade (and folks they need to be short, a 12 or 24 inch tanto or near kodachi is inefficient at body-to-body contact while in the midst of a grapple) to "cut the attacker off of him" before he gains space and transitions to rifle.
While neither appears to be a highly skilled grappler there is some technical stuff going in. Skill at grappling is an essential platform for this kind of thing.
It goes without saying that no matter the era....even when the weaponry is different - certain dynamics at close range stay the same.