It’s a very interesting finding. My take on this has long been that anti-spoilerism is wrongheaded primarily because the sign of something being really good is that it stands up well to foreknowledge of the ending. If you look at Romeo and Juliet or Season 3 of The Wire, part of the pleasure in seeing the artistry with which the tragic conclusion has been set up and rolled into motion over the long arc of the plot. Something that requires you to be genuinely surprised by the “twist” at the end to be interesting is doing something much cruder. That’s one reason “he woke up and it was all a dream” endings are so lame. There’s no storytelling machinery that sets them up that can be appreciated on re-viewing.