How does "show plot for unwatched items" work?

I see there is a Krypton setting to show plots for unwatched items (Settings > Library > Video > Show plot for unwatched items). When using Estuary, "* Hidden to prevent spoilers *" is displayed in place of the plot when this setting is turned off. I'm not sure how this works though, as the localized string (#20370) is not found in any of the Estuary XMLs. In the Mimic skin, the plots continue to be displayed even after the setting is turned off.

Thanks!