[Bug] Use manual subs if available

[quidnu]

Manual subs should be used if available but only auto-subs are downloaded.

This thread yt-dlp/yt-dlp#2262 might be relevant

[NotJoeMartinez]

I chose to use --write-auto-subs because some channels, particularly streamers, upload their live chat instead of subtitles. Here's an example video.

This writes an audio transcript:

yt-dlp --skip-download --write-auto-sub "https://www.youtube.com/watch?v=nctqc8FBJ2U"

This writes a Twitch chat:

yt-dlp --skip-download --write-subs "https://www.youtube.com/watch?v=nctqc8FBJ2U"

However this is a rare occurrence, so I agree that the default option should be manual. We should still provide an option to override this default. Thanks for your input.