Monotonicity intuitively seems like it would be desirable, but I'm struggling to see how the effect described in the video actually matters in practice. It seem

Monotonicity intuitively seems like it would be desirable, but I'm struggling to see how the effect described in the video actually matters in practice. It seems vanishingly unlikely that candidates 2&3 would be eliminated in a tie (and you can just change the rules to force a re-vote/runoff in that case if you really think it's a bad outcome, similar to how you'd handle a tie in FPTP). And even then, the outcome of picking the first candidate when 2&3 are tied doesn't seem explicitly unfair. I'm sure there are other cases where this can show up too though, and maybe some of those do seem unfair. I can see how ex post, one could say "if I had ranked my choice lower, they would have done better", but it's not clear to me that this property actually informs any real-world voting strategy ex ante. Basically, this seems like a somewhat academic property that most voters probably wouldn't care about, so it's not clear that a lack of monotonicity would actually impede IRV from popular acceptance.