What is the purpose of this mode? It seems to suggest that the camera angles will align more closely with the Multirotor angles relative to the horizon. But I bought this 32 bit 3Axis gimbal system so that I could keep my camera level at all times except to RC override pitch.

"Follow Flight Controller – camera is controlled from RC together with the mixed signal from
an external flight controller (FC). Almost every FC has servo outputs to drive a gimbal. It feeds
the information about the frame angles to this outputs, in the PWM format that all servos
understand. SimpleBGC can get this information and use it to control a camera. It is necessary
to connect and calibrate external flight controller (see EXT.FC GAIN settings). After calibration
you can setup the percentage values for ROLL and PITCH axis, so the camera will follow frame
inclinations."