Works in RBGs, use it while you can.
You would have to jump from the very top of the little ledge into the corner of the "wheel" that is mounted on the wall on the Horde side Flag Room. From there, you can keep jumping and go if you happen to get stuck, turn your RP walk on and slowly walk back just a bit then continue jumping into this spot.
Please note that you are not 100% safe as ranged can still attack you depending on where you stand in this glitch.
What you will need for this:
-Movement speed inc. (pref Ghost Wolf, Swiftness potion) *Speed boot buff works too*