This is a simple firefox extension that redirects videos from their watch page to their embed page created with heavy assistance from ChatGPT since I couldn't code myself a new bed let alone an extension.
This is mostly for myself as I tend to like in-browser fullscreen over actual fullscreen. This allows you to click on the extension icon in your toolbar while watching a video. When clicked, it will redirect to the embedded version of that video. It does nothing else.
You can install the extension from here.