To sync thinking each other let’s say more long.
In the video that is a quite special drone. It seems that the position and attitude controllers of PX4 are not used but a special mixer seems to be made for attitude control for this special drone.
So now a position control method, ‘X-Y control’, is needed to it. If the X-Y means the two axes of the quadcopter body it is simple to move toward those axes by just tilting roll and pitch so the position controller is not needed.
But if the X-Y axes means the two axes of fixed world it shoud know current heading direction and compare it to the target direction and then calculate adequate roll and pitch angles. So this is a position controller.
In this position control, the RC sticks command the X-Y velocity of the drone in world coordinates frame as a stick is moved left, right, up and down. For X-Y-Z and heading control, 4 control inputs of RC are used. The 4 inputs may be generated by QGC by making push buttons on the screen by change the code of QGC.
Is it right?