Thanks for the videos, Iceman.
I must admit to being somewhat perplexed by the enormous effort that clearly goes into the making of these videos, and the contrasting complete absence of any kind of rigour in the designs of the experiments or analysis of the outputs. Filming an object at long range, plugging the heights and range into a calculator and concluding that the earth must be flat is completely ignoring refraction, which is often, as it is in the videos you've posted, very apparent in the footage shot. It's not clear what the creators are suggesting - are they saying that such refraction effects are impossible? In which case we need to go to basic lab experiments showing that it very much is. Or are they saying it could happen, but are challenging the amount of refraction that might be possible? In which case, why? What is the basis for this challenge? If there was genuine curiosity as to what is going on, why not repeat the experiments at different times of the day and different times of year - why not try to get results at a time of known low refraction?
If you wanted to set up a demonstration of extreme atmospheric refraction, making possible the viewing of objects far beyond the expected visible horizon, then you would do it at night over a cold or frozen lake. The more extreme the temperature gradient, the better.
If you, on the one hand, are going to claim that distortion in the air between the camera and the flashing lights allow the lights to be seen, then you cannot, at the same time claim that distortion in the air would not cause stars to disappear or appear.
I can claim it, and I do - the two things are not mutually exclusive. The area of maximum refraction occurs across the lowest layers of the atmosphere, along the earth's surface - that's why the sun and moon lose their apparent circular shape and often become wobbly as they set, and why the shimmer appears in those videos Iceman posted. But, as I said earlier, away from the horizon, refraction effects are minimal, which is how marine navigators can safely navigate using star shots to plot their lat and long.
To pick just one of many FET problems from my previous post(s), consider just the two pole stars, Polaris and Sigma Octantis. Their behaviour simply doesn't match what you would expect if the earth was flat. Their elevation or altitude angle almost perfectly matches the observer's latitude in their respective hemispheres. If you were to attempt to calculate their apparent range based on this fact and a flat earth, you would get completely different results depending on what latitudes your two observation angles were taken from. This cannot be correct, and there is no possible distortion effect that could correct this error for every observed angle to give the same result for all latitude combinations, whilst preserving the constant angular separation between the pole stars and their neighbours. Try it - it doesn't work.
Furthermore, FET issues deepen when you consider that two observers in, for example, South Africa and Australia can observe Sigma Octantis at the same time - there is a small overlap, depending on the time of year, in the hours of darkness for the respective continents. And those two observers will see Sigma Octantis on the same heading - due South, which on the monopole FE map has them standing with their backs to the North pole, which means they facing in different directions, at roughly right angles, and yet are observing the same celestial object at the same time. There is no credible explanation for this, and no feasible distortion mechanism that can explain it within FET. This debate is ongoing on another thread in the FE theory forum, and we are awaiting a reply from Tom on it. I'll be interested to see what he says, as I will be in your thoughts on this as well.