Youtube video downloader browser extension
Step 1: Click this link to download the "tampermonkey" extension
At this time, the extension program is not available, you need to perform step 2
Step 2: Click this link to install the "tampermonkey" extension
Click the install button
The effect of the installation is complete
There is this red download button on any YouTube video page, clicking it will jump to the page to download mp3 or mp4.