Extract Kaltura player transcripts via a11y snapshot, not APIs

Kaltura embeds (e.g. inside an LMS via external_tools/retrieve) show a transcript panel only after you click Play. Once it renders, every caption line appears in the chrome-devtools a11y snapshot as a button labelled 'Jump to <time>. <text> . Press Home...'. Save the snapshot to a file and grep/sed those labels to get the full transcript text. You don't need session tokens or the Kaltura API. Opening the embed's retrieve URL directly in its own tab is simpler than working through the iframe on the page. Videos that are music plus on-screen text yield only '[music]' this way. For public YouTube-sourced clips, yt-dlp --write-auto-subs works for most, but some get 'Please sign in' bot checks.