This video explains it clearly, so here it is: youtube.com/watch?v=a1ulBJ3Gew0&feature=youtu.be
This jump allows you to get from the defender’s area near the last objective on Chapel up onto the bridge usually used by the attackers. Without using the ramp!
I found this on my own, someone may have already found this, and it could be common knowledge for all I know. But I will at least bring it up again if it has been found before.
I still wish that I was a the first though.