I summoned a couple of zombies with enchanted armour for an experiment, and discovered that the helmet of a zombie will appear unenchanted. However, when I bring my crosshair over to the zombie's hitbox, the helmet will appear enchanted again. If i move it away, it will not appear enchanted. 
Zombie helmet will appear unenchanted no matter what if distance from zombie is longer than a few blocks. However, this is not shown in the attatched video.

• https://bugs.mojang.com/secure/AddComment!default.jspa?id=402537