The iPhone Duo tabletop layout mirrors every presented frame into the
lower half, blurred and fading out, like a screen standing on a glossy
table. The render view blits a quarter-resolution copy of the display
framebuffer into a ring of IOSurface-backed buffers (no Y flip, so the
surface is already mirrored) and hands it to a CALayer hosted by
MPVReflectionView; the simulator's software renderer feeds the same
layer a flipped CGImage. Off during PiP, for audio-only streams, and
via the new Playback → Foldable → "Reflection Below Video" setting.
