what he said is correct! most of the little cameras used to beam video back to us on the ground will be something between 5 and 12 volts, 5 is probably most common. more of the video transmitters, OSD boards, and even the little power distribution boards are now providing 5v and 12v DC outputs for cameras but like
@John Doecliff said, look at what you're going to buy and match up the ins and outs of voltage requirements before buying anything.
if you just want to record then slap a Legend/RunCam/Mobius on there and fly fly fly