New? Coop glitch
LuckyRJ and I were playing through a PTI map on the workshop before;
We know of the crouching cubes under fizzlers, but did any of you know it also works for walls?
Props to RJ to find it.
http://youtu.be/cQkRX5qOYWU
Yeah. People have used the ceiling in challenge mode so they don't need to crouch. Never seen the wall though. Nice find 
ok i see - yes i was actually shocked myself but when you think of it more clearly not many hammer made maps actually have the fizzler models on the floor, so my guess is that this wont be able to be exploited in most hammer made maps just PTI maps where the fizzler models are on the floor 
This glitch is not new. People have used it. It's in coop PTI maps only, unless Valve fixes the grating.
It's more about the wall glitch; rather than the grating.
Getting gratings to work properly is always a huge problem unfortunately.