You just have to left-click or right-click > save link as... Right-click with Chrome gives your video file a pretty name based on the video title.

Since version 1.2, the link is good even when you change video in a playlist (album) without refreshing the page.

This script has been tested with :

• Tampermonkey / Chrome 58
• Tampermonkey / Firefox 53
• Greasemonkey / Firefox 53