yt-dlp --embed-metadata --embed-subs --sub-lang "en.*" <url>
wvp extensionwvp extension, locate the page url in the keys section and click + to expand the entryn-m3u8dl-re <url> --key <key> --auto-select -mt -M mkv --write-meta-json false
wvp extension.note: as of late, it seems like weverse has changed some things on their back end and wvp is picking up a manifest url that does not allow you to download any streams. if this is the case you can instead open the dev tools and filter for mpd to find the correct url.
vttcopy -> copy urlsingle subtitle
ffmpeg -i vod.mkv -i <url> -metadata:s:a:0 language=kor -metadata:s:s:0 language=<lang> -c copy mux.mkv
multiple subtitles
ffmpeg -i vod.mkv -i <url> -i <url> -i <url> -map 0 -map 1 -map 2 -map 3 -metadata:s:a:0 language=kor \
-metadata:s:s:0 language=<lang> -metadata:s:s:1 language=<lang> -metadata:s:s:2 language=<lang> -c copy mux.mkv