Well, it didn't take long for me to confirm that atmospheric refraction does indeed play a very significant role when performing such experiments...

**Effect of atmospheric refraction**
If the Earth were an airless world like the Moon, the above calculations would be accurate. However, Earth has an atmosphere of air, whose density and refractive index vary considerably depending on the temperature and pressure. This makes the air refract light to varying extents, affecting the appearance of the horizon. Usually, the density of the air just above the surface of the Earth is greater than its density at greater altitudes. This makes its refractive index greater near the surface than higher, which causes light that is travelling roughly horizontally to be refracted downward. This makes the actual distance to the horizon greater than the distance calculated with geometrical formulas. With standard atmospheric conditions, the difference is about 8%. This changes the factor of 3.57, in the metric formulas used above, to about 3.86. This correction can be, and often is, applied as a fairly good approximation when conditions are close to standard. When conditions are unusual, this approximation fails. Refraction is strongly affected by temperature gradients, which can vary considerably from day to day, especially over water. In extreme cases, usually in springtime, when warm air overlies cold water,

__refraction can allow light to follow the Earth's surface for hundreds of kilometres__. Opposite conditions occur, for example, in deserts, where the surface is very hot, so hot, low-density air is below cooler air. This causes light to be refracted upward, causing mirage effects that make the concept of the horizon somewhat meaningless. Calculated values for the effects of refraction under unusual conditions are therefore only approximate.[5] Nevertheless, attempts have been made to calculate them more accurately than the simple approximation described above.

Horizon - Wikipedia Emphasis added

The article is packed full of mathematical formulas. If anyone is interested enough to do the math, my bet is that the bridge video show EXACTLY what one would expect to see on a globe with a thick atmosphere.