UltraWideo

UltraWideo is a Chrome and Firefox extension that zooms, stretches or crops video so it fills your screen without black bars. It works on inline and fullscreen players across YouTube, Netflix, Twitch, Disney+, HBO Max, Amazon Prime, Crunchyroll and most other sites that play video. It's useful for ultrawide monitors, and also for odd setups like playing YouTube on an old 4:3 CRT.

The free version needs no account. It includes display modes (normal, upscale, stretch, custom), manual scale and pan controls, keyboard shortcuts, and swipe, pinch and scroll gestures for touchscreens and trackpads.

Pro adds per-site and per-page settings, a mode manager that trims the mode cycle, and letterbox detection that crops black bars baked into the video, including on protected streams through a Measure tool. It also adds an ambient light glow around the video, adaptive sharpening, and cloud sync of settings between browsers and devices.