Screen recording extensions usually ask for permission to “read and change” data on the sites you visit, and they keep that access for as long as they’re installed, updating themselves in the background. Many also upload recordings to the developer’s servers so they can give you a link.
A web recorder works the other way round. It sees only the tab, window or screen you pick each time, and only while it’s recording. recorder.video keeps takes in your browser’s own storage and never uploads them; when you’re done, you download the file. There’s nothing to update, nothing to remove, and it works in any desktop Chromium browser, including on a work computer where you can’t install extensions.
What an extension can do that a page can’t: start from the toolbar on any site without opening a tab. If that matters, keep recorder.video pinned as a tab, or install it as an app from Chrome’s address bar where Chrome offers it.