Method to allow writing of WARC file format as output.

[openAccess]

Checklist

• [ x] I'm reporting a feature request
• [ x] I've verified that I'm running youtube-dl version 2019.08.02
• [ x] I've searched the bugtracker for similar feature requests including closed ones

Description

The Internet Archive uses youtube-dl rather extensively for youtube archiving. Great piece of software - thank you for your efforts.

Being an Archive we have a specific objective which is to record the complete interaction of acquiring and saving the video. Currently we do this in a simplistic way - we get the yt url from youtube-dl and then use that url to download the video and record the complete http interaction into the WARC format (Web ARChive format). Other than providing the url yt-dl is not involved.

This works in most cases but is somewhat limiting - for example - each video source requires a unique solution. A more useful scenario would enable us to easily record a WARC (Web ARChive) file regardless of the http source selected. This might be accomplished either by
hooks or adding WARC output as a feature (or your preferred solution). WARC output is currently supported by curl if you wish to experiment. It is a widely excepted format and is not a complex specification.

More about the Archive
https://archive.org/

More info on WARC format:
https://en.wikipedia.org/wiki/Web_ARChive