Tabs other than Install build their checkboxes lazily on first visit.
Import populates $sync.selected* and calls Reset-WPFCheckBoxes, but
that only touches checkboxes that already exist in $sync, so any tab
not yet visited gets its controls built later with default (unchecked)
state and never reflects the import. Re-apply Reset-WPFCheckBoxes right
after a tab's controls are built so it picks up existing selections.
mpv has no official Windows installer; winget id shinchiro.mpv is the
de facto standard Windows build. Choco mpv/mpv.install are flagged
"Possibly broken" upstream, so winget is the sole install source.
Vinicius Costa Amorim