How can I update youtube-dl?

Try

sudo pip install --upgrade youtube-dl
That will upgrade youtube-dl. If you get this message:

sudo: pip: command not found
try

sudo apt-get install python-setuptools
sudo easy_install pip
sudo pip install --upgrade youtube-dl

To install the latest youtube-dl in Ubuntu, run the following commands in a terminal:

 
Step 1: udo add-apt repositoryppa:nilarimogard/webupd8
Step 2: sudo apt-get update
Step 3: sudo apt-get install youtube-dl

To download a YouTube video, use the following command:

youtube-dl YOUTUBE-URL