[VEVO] Support for captions

[nyuszika7h]

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Description of your issue, suggested solution and other information

It seems VEVO has subtitles on their site despite not displaying them there, only on YouTube. From this playlist:

#EXT-X-MEDIA:TYPE=SUBTITLES,GROUP-ID="subs",NAME="English",DEFAULT=NO,AUTOSELECT=YES,FORCED=NO,LANGUAGE="eng",URI="subtitles/subtitles_en.m3u8"

And the subtitles are under http://hls-aws.vevo.com/v3/hls/2016/07/USH5V1622713/f27f4e03-7554-4b9b-bd83-74e8e42477e2/subtitles/en/0001.vtt, 0002.vtt and so on.

Would be nice if those could be downloaded directly instead of having to download them separately from YouTube.

[yan12125]

Subtitles in M3U8 are not supported yet.