asie@asie@mk.asie.pl
Rumoredly, YouTube is getting rid of custom ".ytt" subtitles from their website. Here's a quick shell script if you need to archive them in a few formats for all languages:
#!/bin/sh
for i in vtt ttml srv3 json3; do
yt-dlp --write-subs --all-subs --sub-format "$i" --skip-download --compat-options no-live-chat "$1"
done