Hacker News Reader

I believe by "darken" they mean the ability to turn off the screen while watching a video, or more likely, listening to music.

View on HN

I'm not OP, but for me, on YouTube I literally mean 'darken'. Similar to a dark mode on desktop. Whereby the comments area and backgrounds get dark, but without the video going to fullscreen.

Reply on news.ycombinator.com