I bought this 5v step down for the video transmitter. Not sure if it's the Bec or the transmitter but, I have static in the video and it's motor rpm related.
FuriousFPV Micro BEC with Selectable 5V / 12V 1.5A Output
This is an efficient rectified step-down switching regulator made by FuriousFPV. Despite it's small footprint, it can provide 1.5A continuous output current at 5 or 12 volts! FuriousFPV included an output filter to reduce noise. It prevents interference from affecting the Flight Controller or FPV system.
The standard output voltage is 5v. To change the voltage to 12v, bridge the two solder pads on the back of the BEC.