How to remove blinking red dot from video

If the background is constantly moving, but the red reflection is always in the same place in the video. In that case, you may be able to create a feathered subtraction mask over the reflection, so there is just a hole in the video that removes the reflection. Then, you can try duplicating the footage layer, shifting the position of the bottom copy to the background to fill the hole, and maybe adding a little blur to the bottom layer to help hide the edges. 

Another approach would be to timeshift the bottom copy of the footage and animate the opacity of the mask so that the mask makes a hole in the video when the light is on. Because the blinking tally light is running at a constant rate, a simple loopOut() expression with three keyframes would animate the opacity of the blinking reflection for the entire shot. Again, you may have to blur the bottom copy to hide the time difference.

Another option would be to create some other reflection for the frame using Photoshop, which does not obviously look like a flashing tally light, and drop it in the shot.

If those options do not work because the reflection moves around on the windshield or the background changes too much, you are probably stuck with Content-Aware Fill. Without seeing a few seconds of the shot, that's the best I can come up with.