I expect that one source of the problem is seen in equating these two situations. On one hand you have 100 copies of the same movie. On the other hand, you have 100 distinct humans you could pay to save. To draw a direct comparison you would need to treat these as 100 copies of some idealized stranger. In which case the scope insensitivity might (depending on how you aggregate the utility of a copy's life) make more sense as a heuristic.

And this sort of simplification is likely one part of what is happening when we naively consider the questions:

How much would you pay to save a random stranger’s life? How much would you pay to save 100 strangers?

I wonder how this experiment would change if you presented lists of names? If you encouraged a different model for the 100 strangers.

I think delving into the difference between untrue and impossible would help here. In a model which contains rules distinct from state, "untrue" means "same rules, different state" (usually a state that's not obtainable from the current state and rules). "impossible" means "unsustainable under the rules".

That distinction between rules and state is only in our minds/models, though. In the actual universe, if there is such a distinction to an outside observer, it's lost to those of us stuck in it, because we can effect neither portion of reality.

note: I'm saying this more confidently than I feel. I would deeply appreciate pointers to any evidence that the universe has rules and state which are somehow alterable separately.

As to "hypothetical" vs "counterfactual", you're right that this isn't a blanket synonym. There are hypotheticals that have unknown truth value rather than being known falsehoods. For purposes of this discussion, and for most interesting thought experiment, the hypothetical situation given is simply false - it does not exist as described in the universe.