How I've been installing and updating the YouTubeTV plugin on Ubuntu Server 16.04...

Download the latest tar.gz release of the plugin from the author's GitHub page here

wget https://github.com/kolsys/YouTubeTV.bundle/archive/v4.6.tar.gz

Extract the file

tar -xvf v4.6.tar.gz

This will create the YouTubeTV.bundle-4.6/ folder. This needs to be placed in the Plex Plugins folder, the release number needs to be removed as well. I normally rename and the move but it can be done in one as follows

mv YouTubeTV.bundle-4.6/ /var/lib/plexmediaserver/Library/Application\ Support/Plex\ Media\ Server/Plug-ins/YouTubeTV.bundle/

The official Plex helpsheet says that you may need to reboot the server, but for me this worked with a refresh of the page.

To update the plugin I moved the folder in Plugins back to my home directory, then moved the new one in and refreshed the page.