Wikipedia
Gun cameras are cameras used primarily in aircraft to help measure tactical effectiveness. These cameras are triggered by the firing of a weapon, hence the name.
The use of gun cameras first became common for gunnery training in the 1920s though examples were used during World War I by the British Royal Flying Corps. A special version of the standard Lewis Machine gun was manufactured as a Camera Gun. During World War II, gun cameras were commonly used on operational aircraft to record kills of enemy aircraft. Some of this footage survives to this day and is often the source for stock footage in World War II movies, TV shows or video games.
The term guncam may also refer to software that records video game footage, it is often triggered by the firing of a weapon in a way similar to the original guncams of World War II. Some popular examples of this software are Growler Guncam and Java Guncam.
Gun Camera may also refer to a video camera mounted on a gun where the camera has a point of aim indicator, typically a reticle in the form of a crosshair or a red dot, that shows in the video where the gun is being pointed.
Usage examples of "gun camera".
The saucer goes down, almost to the ground, and the that they had some interesting footage in the public affairs F-16 goes by and that's it for the gun camera.
A gun camera, maybe even a satellite photo, might have picked him out from among the swarming masses of Big Uglies around him.