Connect your webview page's network access manager finished signal with replyfinished slot of your class.
connect(webviewptr->page()->networkAccessManager(), SIGNAL(finished(QNetworkReply*)),this, SLOT(replyFinished(QNetworkReply*)));
In replyFinished you will get the QNetworkReply pointer for all resources like images, video etc. By using function url of QNetworkReply class you can check what kind of resources they are and read the content of those files.