Very interesting link.
However it only describes how to capture the video, meaning how to display the camera output in the browser.
From there, you need a server side software to either broadcast (for network communication usage) or record it into a file (for alterations and posting elsewhere. So nothing that only a Webflow page could do, even with some additional code. What you describes requires quite a lot of work, especially on difficult libraries like FFMPEG, a library meant to write video in files. There are also all the srver aspects, what to do with the files, manage errors and interruptions, and the Facebook posting using the developer API and dealing with the publishing limitations of it.
This is totally something my company can develop but it represents quite a budget.