Removed useless printing information

The name of the user doesn't add a lot to the output of the script
and it augments maintenance.

The outputdir is just a reprint of the argument, that it's automatically
reprinted for each video.
Small optimization, target_dir is constructed outside the loop, and the
directory creaton is guaranteed
Added new option to download videos directly from the CDN source.

This avoids the use of youtube-dl, for the moment subtitles are not
supported.
Added support for fun (france universite numerique) mooc