Nothing came up when I looked up the exploit, due to the titling being weird.
Basically, when you approach BET, there is a cliff you can jump down on the right side. Not really a cliff, but just a ledge below the ground.
I was on my hunter, and I jumped down there to avoid dying. I noticed I could still shoot up at guys who were near the flag cap part. I don't have a screenshot, I'll try to upload one.
So, basically, you can shoot through a wall/ground where you are not visible to the people on top near the tower, allowing you to freely heal/cast/shoot them while out of harms way.
Why this is an exploit: You shouldn't be able to shoot arrows through 20ft of rocks.