As you probably know, the Waypoints feature in DJI Go lets you create a pre-recorded flightpath and then fly it "on autopilot".
It turns out that if you pause a waypoint flight in progress, pushing the right stick forward moves forward in the programmed flight, and pushing the stick backwards moves backwards in your flight. That's very cool, and since you can vary the amount you push the stick forward/backward this gives you the ability to vary you flight speed throughout the flight, anywhere from full speed backwards to full speed forwards through the programmed flight. (In this context I think that "full speed" means max waypoint flight speed, not max Phantom speed, but I haven't been able to confirm this yet.)
It turns out that if you pause a waypoint flight in progress, pushing the right stick forward moves forward in the programmed flight, and pushing the stick backwards moves backwards in your flight. That's very cool, and since you can vary the amount you push the stick forward/backward this gives you the ability to vary you flight speed throughout the flight, anywhere from full speed backwards to full speed forwards through the programmed flight. (In this context I think that "full speed" means max waypoint flight speed, not max Phantom speed, but I haven't been able to confirm this yet.)