New ghost hack?

I was playing gm the other day as gr and just doing the usual then I noticed a ghost that I couldn't see at all, like through out the whole game I didn't see him at all. At first I thought it was just a rly good bhopper, but then even his teammates were saying that he was invisible the whole time (even when walking around).

So i saved the replay and watched it. And fair enough he wasn't bhopping at all.
The replay shows him visible the whole time, but I assure you, he wasn't.

Basically, he stays in the same position(hand by his sides) and sliding around like a zombie, and he didn't make any foot step noises nor water splashes.

Anyways, here's a ss, I'll make a video during the weekend to show it better.