I am trying download this link https://www.youtube.com/watch?v=Pi3bc9lS3rg which is completely working on Ubuntu server but not on my mac. I repeatedly get this Warning:
WARNING: unable to set language: [youtube] Pi3bc9lS3rg: Downloading webpage
and also following error
ERROR: Unable to download webpage:< urlopen error [Errno 8] _ssl.c:504: EOF occurred in violation of protocol>
According to its github, https://github.com/rg3/youtube-dl/issues/2219, the problem is very likely to be an outdated version of your Python installation.
As a workaround, you can use the .exe instead of the .py, but the solution is just to upgrade your Python.