Although I resolved my own issue just now, the whole yt login process could still use some revision and improvement.
I just followed the instructions from open video downloader on how to get cookies manually for yt.
Long story short, install this extension (also available for chrome) https://addons.mozilla.org/en-US/firefox/addon/cookies-txt/
Go to YT, make sure you're logged in and focused ON (current tab open) yt site, then open the extension and tell it "current site" and save cookies.txt to a download location, then copy paste the file to the SF program directory. If Windows, it will require Admin permission to do so. Restart SF and go to the YT option, the "Login" button will quickly change to a logged in status, for me it is oddly the letter "M". Probably because my Google account starts with an M.