This will run a script to download all new videos locally from my favorite YouTube channels.
Update the paths in each of the files to match your system.
Move the org.elroyjetson.yt.plist to your ~/Library/LaunchAgents directory
Change the permissions on yt.sh so that it is executable
chmod 755 yt.sh
Load the launch agent.
launchctl load ~/Library/LaunchAgents/org.elroyjetson.yt.plist
Further instructions can be found at elroyjetson.org