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The 120m tall object 60 km away would appear twice as tall (40m) compared to the 20m tall object 20 km away.

Thanks. I tried to boil down the argument in the video to a simple case with simple numbers.
I really hope Ladislaus comes back to explain why this wouldn't be the case. This is important, because Ladislaus dismissed the argument in the video as being "utterly idiotic" and discrediting "globe earthism".

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It's a fake accusation for him to say a video showing amazing power zoom is "utterly idiotic" -- because for him, using a zoom improperly (without a solar filter) is his idea of showing that the sun can be made to "rise" from the horizon by increased power of zoom. Ladislaus defends the utterly idiotic while falsely accusing accurate analysis of the same. He's got it backwards!
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Ladislaus is not going to answer your well-thought-out question because he is not capable of thinking logically in regards to geometrical perspective. He has no idea what you're talking about. To prove my point, if he ever does reply he will continue with a series of inquiries that imply your negligence to consider other factors such as barrel distortion, humidity, refraction, temperature, time of day, type of surface (water or hard earth), heat differential and the like. He will attempt to make a mountain out of a molehill because he denies the whole point of your question. It cannot be simple for him and his ilk, it must be far more complicated such that no correct answer is possible.
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He weakly and ignorantly buys the flat-earth nonsense and deceptions eagerly and without any objective inquiry, all the while claiming that he has a "great talent for shredding bad arguments."
More like, he has a great talent for sticking his own foot in his own mouth.  
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A more general form that covers both versions could go as follows:
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On a fair, clear day, a man on a hypothetically "flat" earth is standing on flat ground, facing a clear view of two distant objects, also on flat ground, the closest of which is 20 kilometers away from him; there it stands 20 meters tall. In nearly the same direction the man sees a second object at 60 Km away, standing 120 m tall. 
- A) Which direction does the man have to walk: toward  the objects, further away from them, or not at all -- such that when he lies on the ground to look at them, the two distant objects would appear to be the same height, and 
- B) How far must he walk (toward, away or zero) to arrive at this position (where the objects would seem to be equally tall)? 
- For extra credit, by what magnitude and in which direction does this (B) distance change if the man had from the start viewed the two distant objects from the prone position, instead of standing?
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The original question, "...which of these should appear taller...?" would be redundant since it is displaced by part (A) in the general form, above. Additionally, anyone attempting to solve the problem who complains, that which object from the start appears taller has nothing to do with which way the man would have to walk in order to see them appear the same height, does not understand the problem at all, or is ignorant of how perspective works. IOW it exhibits nescience typical of flat-earthers.