He's talking about the hump on the shoulders and the color/shadows on the front. Kinda looks like the body of an Elk if you're clicking thru game cam pics pretty quick.
Optical illusions are a funny thing. I grew up in elk country, so it didn't immediately strike me as that. But, I blew it up to 500% and it appears that the "hump" is actually something it the background. You can see a distinct line between the back and the object. If it had been antlerless, it really would have taken a third glance. But, with the "hump" and the "shadows", I can see the illusion now.