Happy to be the first to try based on my flying of Phantoms 1 & 2 and Inspire 1.
In normal mode, the right stick, controlling forward/backward and left/right movement, sends the craft in that direction based on which way the front of the quad-copter is pointing. Therefore if the front of the quad-copter is pointing towards you, right becomes left, forwards becomes backwards etc. If you imagine a soldier on a parade ground and you tell him to move forwards, backwards, left or right he moves in the direction, based on the way he is facing and nothing else.
If you set the quad-copter to Course Lock, it uses a pre-determined direction as its continual reference point or line of travel. This is usually the direction that it was facing when you took off. Therefore regardless of the direction the quad-copter is facing, forwards is always forwards along the line the quad-copter was initially pointing, and not the way it happens to be pointing at the time. Back to parade ground and our obedient soldier. If you tell him to move north, south, east or west he moves in that direction regardless of which way he is facing. So it is with the quad-copter when you move the right joystick in the 4 main directions.
Good luck and safe flying