similar to calculating temperature to 0.01 degrees.
but that was a high end, color camera, with self-leveling head.
after you do the first video, you put the camera into the hole. down, then it turns, often full of water, so you push it, ever-so-much... then a bit more.. op's forgot to zero....
yeah, in about 3-5 feet and off you go.
taking turns like Mario Andretti, the apex is the shortest length, but the cable makes the full sweep. so there is no way to walk into the warehouse and use some caulk or paint to be exact.
the mid-point cleanout really is the best marker. you know you went 12ft 7 inches so can be within inches when you dig.
My point is that some machines have an input for distance and can put that on the recording.
here is one I put up on youtube only to the inch.
example of a clear camera.
