Plex Ambilight

Plex Ambilight adds ambient lighting effects to the Plex Web video player. Colors are sampled from the edges of the currently playing video and projected as a soft glow into the surrounding dark areas of the page, similar to Philips Ambilight TVs.

https://github.com/iosue-iulianus/plex-ambilight

Features:

In-player controls — a lightbulb icon in the Plex control bar lets you toggle and adjust settings without leaving the player

Adjustable intensity, spread, and blur settings

Automatically adapts to any aspect ratio (4:3, 16:9, ultrawide)