Greasemonkey is a powerful browser extension that allows you to customize how web pages look and function using small bits of JavaScript called "userscripts". While Greasemonkey itself doesn't download videos, it serves as the platform to run specialized scripts that add download buttons directly to your favorite video sites. How to Use Greasemonkey for Video Downloads
To start downloading videos, you need to set up the environment in your browser: How to install and use userscripts greasemonkey download video