If i understand this correctly, this means it shuts off when voltage drops below 5V.
The BEC is so called because it eliminates the need for a separate battery for the transmitter. (I would assume). BEC's are often
stanalone circuits that keep your servos running when you fry your ESC trying to break the sound barrier. The plane will lose power but you can glide in for an emergency landing ..(EMERGENCY LANDING !!!)