Install youtube to mp3 or mp4 google chrome extension - YouTube converter
browser addons - Chrome add-on to download YouTube videos - Super User
GitHub - domsleee/YouTube-Downloader: Download YouTube videos and audio in multiple formats
YouTube™ Multi Downloader 🚀💯 - yt1s.com (MP3, FHD, MP4, HD, SD, 3GP / NO ADS 🚫)
How to install extension for safari to download Youtube videos
GitHub - TraceHeritage/YoutubeRestoreFlash: Replaces the default YouTube player with a flash alternative. Project aims to restore YouTube functionality to old systems which can't use modern web browsers.
Youtube Downloader Gold :: Add-ons for Firefox
GitHub - mahmutyukselmert/youtube-mp4-download-tempermonkey-script: A script file that allows you to download videos for Youtube. Note: It works with the Tampermonkey plugin.
software recommendation - How do I download a YouTube video? - Ask Ubuntu
YouTube™ Multi Downloader 🚀💯 - yt1s.com (MP3, FHD, MP4, HD, SD, 3GP / NO ADS 🚫)
browser addons - Chrome add-on to download YouTube videos - Super User
Local YouTube Downloader
Download YouTube Videos as MP4 for Greasemonkey
Download YouTube Videos as MP4 Add-on for Firefox
Download Youtube Videos As Mp4 Greasemonkey Script - Colaboratory