Settings → Playback → "Play trailers in details background" (off by
default) hands the trailer embed URL to the detail shell; the new
app-hero-trailer-backdrop plays it muted and looping under the scrim
after three idle seconds with a corner mute toggle. It never starts under
prefers-reduced-motion or with saveData, and stops while the hero is off
screen or the window is unfocused. Xtream and Stalker movies and series
are wired; M3U has no trailer source.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>