Youtube Downloader Chrome Extension
This allows Google Chrome users to download and convert YouTube videos to mp3 (320) kbps files and also videos with a variety of high quality options 2160p (4k), 1440p (2k), 1080p (HD), 720p (HD), 480p, 360p, 144p etc. This video quality is supported for all available video formats (MP4, WEBM, 3GP).
Follow steps 1 to 3 below for installation
Then the install dialog will appear, please install it
Download Youtube Downloader
Visit https://www.youtube.com/new to check and update your YouTube Layout.
Done, you will find the download button on all youtube pages like the picture below.