Two faults behind the 429 in the report.
The subtitle languages were a wildcard: 'en.*' also matches every
machine-translated variant YouTube offers — en-en-US and dozens more —
so each download fired a burst of subtitle requests and earned an HTTP
429. Languages are now named exactly, as '<lang>,<lang>-orig'. Turning
subtitles off now really does request none; it previously still asked
for English.
Worse, yt-dlp exits non-zero if anything at all failed, and a caption it
could not fetch was enough to mark a fully downloaded video as failed
and leave the file orphaned. yt-dlp now runs with --ignore-errors, and
success is judged by whether the media file actually landed rather than
by the exit code.
429 also gets its own message pointing at the sign-in setting, which
raises the limit.
vincent
923fd3273f