WKWebView Not detect the the video url of instragram and facebook and netflix video

i want to detect video url of facebook video and instrgram video url but WKWebView gives a youtube video url i already used WKWebView navigation delegate its not give the video url

webView!.addObserver(self, forKeyPath: "URL", options: .new, context: nil)

    override func observeValue(forKeyPath keyPath: String?, of object: Any?, change: [NSKeyValueChangeKey : Any]?, context: UnsafeMutableRawPointer?) {
            if let key = change?[NSKeyValueChangeKey.newKey] {
                print("observeValue \(key)") // url value
                
            }
        }