Any AK with a folding buttstock would be quite concealable, yes. That 5.45 projectile is pure poison, too - very nasty wound ballistics. The side-mounted Russian scopes which fit the AK series would put the AK-74 in the accuracy ballpark for 150-yard shots, but head shots with an AK trigger? That'd be iffy with a very experienced shooter.
That short-barreled Krinkov that bin Laden was always toting around was based on the AK-74. Heyyy...
150 yard head shots can be done with a Red Star triger or any of the 2 stage triggers available on the market. Like I said...this guy is very familiar with the Ak to have this type of "success" with it. He has been trained in another country to use an AK..in my opinion. A bolt action Rem 700 could be effectively shot by a 12 yr. old. The AR is also a very easy gun to shoot accurately...but, the AK has it's quirks. And this guy is dead to rights on his targeting.