This extension in a godsend for Ultrawide OLED monitors. As you know, Youtube does not allow videos in other formats except 16:9 (at most 18:9 on phones) so ultrawide (21:9 and larger) monitors get giant black bars on the side. With OLED monitors that is a big no-no, as over time the middle of the screen will start slowly burning in, and the sides will remain brighter. You want to actively use the entire screen to get uniform burn-in over time, and this extension fixes that problem.