Youtube video upload/download along with captions/ transcript files

I am aware of the youtube api for .net and this question.

The problem that I am facing is that I want to u开发者_开发技巧pload youtube video with captions or more importantly a transcript file and if download them as well. Does anybody know how to do this in C# (silverlight) ?

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Developers Guide: Data API Protocol – Captions

For the C# bit, it's just writing a bit of HTTP.