QML Video element doesn't use QDeclarativeNetworkAccessManagerFactory

Example code:
int main(int argc, char ** argv)
{
    QUrl source("qml/network/main.qml");

    QApplication app(argc, argv);

    QDeclarativeView view;
    view.engine()->setNetworkAccessManagerFactory(new MyNetworkAccessManagerFactory);
    view.setSource(source);
    view.show();

    return app.exec();
}
class MyNetworkAccessManagerFactory : public QDeclarativeNetworkAccessManagerFactory
{
public:
    virtual QNetworkAccessManager *create(QObject *parent);
};

QNetworkAccessManager *MyNetworkAccessManagerFactory::create(QObject *parent)
{
    qDebug() << "create called";  // This is never called, in case of Video element, but works correctly if e.g. Image element is used

    QNetworkAccessManager*nam = new QNetworkAccessManager(parent);

    return nam;
}
main.qml:

    Video {
        id: video
        anchors.fill:  parent
        source: "http://someserver.com/testvideo.mp4"

        autoLoad:  true
        volume: 0.5
        fillMode: Video.PreserveAspectFit
    }
}