Youtube multi-language caption support

[Regen-forest]

If a video provides more than one language of captions, cpdown will copy only the first available language.
For example, in this video, cpdown copies the Arabic captions.
I hope cpdown can provides an option that lets users choose which language they want from a YouTube video that provide more than one language caption.

[ysm-dev]

Oh, that’s a great idea. I haven’t had the chance to test a video with so many languages. Thank you for reporting it.
If I have time this weekend, I’ll update it and let you know.

[Regen-forest]

Much thanks for your work!