( https://github.com/rg3/youtube-dl/blob/master/README.md )
if you've followed our manual installation instructions, you can simply run 
youtube-dl -U (or, on Linux, sudo youtube-dl -U).

If you have installed youtube-dl using a package manager like apt-get or yum, 
use the standard system update mechanism to update. Note that distribution 
packages are often outdated.
Simply go to http://yt-dl.org/ to find out the current version. 
to remove the version of the distribution type: sudo apt-get remove -y youtube-dl

Afterwards, simply follow our manual installation instructions (http://rg3.github.io/youtube-dl/download.html):
   sudo wget https://yt-dl.org/latest/youtube-dl -O /usr/local/bin/youtube-dl
   sudo chmod a+x /usr/local/bin/youtube-dl
   hash -r
from then on you'll be able to update with sudo youtube-dl -U.

youtube-dl is located in /usr/local/bin. Must be in path !
Here it needed as well pkg "rtmpdump".