Ultrawidify is a subscription-based Firefox add-on designed to remove black bars from videos across various platforms like YouTube, Netflix, and Twitch. It features automatic aspect ratio detection, allowing users to enjoy a more immersive viewing experience without distractions. If the automatic detection fails, users can manually adjust the aspect ratio using predefined shortcuts for various formats, including 21:9 and 16:9. The add-on also includes a stretch video option for those who prefer to fill their screen regardless of the video quality.

In addition to its cropping capabilities, Ultrawidify offers unique features like aligning video to one side of the screen and a manual override for player detection to enhance compatibility with various websites. Users can also customize their experience by adding custom aspect ratios and keyboard shortcuts, although this requires some technical knowledge. With its blend of automated and manual controls, Ultrawidify aims to provide a tailored video playback solution for users seeking to maximize their screen space.