Drone video of missile fired at UAP bouncing off..

[confused2]

If the post (object) were also moving, it would appear to be moving at it's own speed plus the speed of my head moving (drone camera).

Attach a line to your backdoor handle. Tie a piece of grass half way along the line. Keep the line taught and run up and down while looking down the line (like a camera) at the door. Are the piece of grass and the door handle always perfectly lined up?

[Syne]

If the post (object) were also moving, it would appear to be moving at it's own speed plus the speed of my head moving (drone camera).

Attach a line to your backdoor handle. Tie a piece of grass half way along the line. Keep the line taught and run up and down while looking down the line (like a camera) at the door. Are the piece of grass and the door handle always perfectly lined up?

A line isn't a camera, which intentionally keeps a target in sight. You can even see the camera repeatedly adjusted to recenter the object in the video. My eyes are an analog for the camera. So you're making up a non-analogous example to simply illustrate your foregone assumption. It doesn't actually reflect the physical situation.

[confused2]

Where an object is appears to be on a surface can be found by drawing a straight line between the camera, the object and the surface. In the case we're looking at I suspect the object is much closer to the surface than the reaper and parallax isn't a factor.. because the .. o can you not see?

[Syne]

It's pretty clear, from the video, that the object is a significant height over the ocean.
The TGT on the display is highlighted while the camera is actively tracking the object (keeping it centered and possibly lasing the target for the missile strike). It reads 3.1 & 2.4 NM (nautical miles) right before the missile strike.
The TGT highlight turns off immediately after the object is struck, indicating it has lost tracking. It reads 6.1 & 4.6 NM immediately after the missile strike.

On the MQ-9 Reaper drone's camera display, the two "NM" indicators refer to two different measurements of distance, in nautical miles, from the target. The numbers represent the following:

Slant Range (NM): This is the direct, line-of-sight distance from the drone's targeting pod to the target on the ground. It is the most critical measurement for weapons employment because it determines the time to impact and the effective range of a weapon like a laser-guided missile or bomb.
Ground Range (NM): This is the horizontal distance, or "as the crow flies," from the drone's position directly over the ground to the target. This measurement is useful for situational awareness and mission planning but is less critical for the actual weapons release.
- Google AI

So the direct line of sight distance, from the drone to the object, is 3.1 slant nautical miles, and once the object is no longer tracked, the distance is 6.1 slant NM... basically doubled.
Using the Pythagorean theorem, we also know that the drone is flying at about 4 nautical miles (24,304 ft) above sea level.
Doing the same for the object shows it to be about 2 nautical miles (12,152 ft) from the drone.

Verifying that the object is about halfway between the drone and the ocean.
Hence parallax is a significant factor, as previously shown.