Resolve public YouTube URLs through external yt-dlp and play selected streams in the existing native window.
Independent bounded network readers keep one authored timeline. Successful seeks clear FFmpeg's sticky aborted-read AVIO error; manifest seekability uses native format flags rather than a top-level I/O handle.
Verified real YouTube playback, seeking, frame stepping, compact mode, cancellation, and the complete native regression checks.
hl-valdemar