Its most likely an M4A1 (76mm), judging by the engine, shape of the decking and the lack of a muzzle brake. Turret looks like an M4A1E8 subtype by the hatches and shape of the mantlet, though E8s usually had the muzzle brake. Would have to see the shape of the drive sprocket and whether it was a VVSS or HVSS system to be sure though. May have been an A2 or A3 that had been equipped with an older style engine (happened occasionally when they were refurbished and sent back to the front), but thats probably a one in a million chance.
Heres the turret of an M4A1E8 from roughly the same angle as the cameraman was standing- pretty much a dead ringer.
And a still from the vid. I'd say (given the mantlet, style of the hatches and general outline ogf the turret) that its definitely an E8 turret. And with that engine, most likely an A1 as previously stated. So almost 100% sure its an M4A1E8.
