Andrews54757/FastStream ? reverse-engineered prompt

Build me a browser extension that replaces videos on websites with a better player so they start faster and don’t keep buffering.

I want it to work on Chrome and Firefox, detect videos on a page, and swap them into a clean player that I can use from the site or from a separate tab. It should handle regular MP4 videos as well as stream links like m3u8 and mpd, and it should support loading local video files too.

Please include useful accessibility features like customizable subtitles, subtitle syncing, keyboard shortcuts, and easy to reach playback controls. It should also let me adjust things like volume, brightness, contrast, and a few audio options, since I want more control over how videos sound and look.

Make it work offline if possible, keep it privacy friendly, and make the interface feel polished and simple. If you need to check current browser extension docs or video playback details online, go ahead.