WEBVTT

NOTE
Zero-cue captions track. The Buy2 narration <video> (StickyProductImage) is a
single always-mounted element that has no source while no section narration is
active; it points its <track kind="captions"> here so the captions track is
never absent (WCAG 1.2.2 / axe video-caption), and swaps in the real
SRT-derived VTT blob as soon as a section video with a caption file plays.