YTCCD

This extension downloads YouTube closed captions in SRT subtitle format. You need to set extension to «srt» and action to «Save To Disk» for «text/srt» MIME type manually via Settings->Preferences->Advanced->Downloads->Add. Otherwise Opera will open subtitles as an unknown type. To download captions select language from dropbox near «Subscribe» button. Then in the «Save as...» window type-in subtitles name and click «Save» button. YouTube don't publish auto-generated subtitles so you can't download them with the extension.