Handle videoSource changes correctly

src/FlightDisplay/VideoManager.cc

@@ -56,6 +56,7 @@ VideoManager::setToolbox(QGCToolbox *toolbox)
 
    _videoSettings = toolbox->settingsManager()->videoSettings();
    QString videoSource = _videoSettings->videoSource()->rawValue().toString();
+   connect(_videoSettings->videoSource(), &Fact::rawValueChanged, this, &VideoManager::_videoSourceChanged);
 
 #if defined(QGC_GST_STREAMING)
 #ifndef QGC_DISABLE_UVC
@@ -91,6 +92,12 @@ VideoManager::setToolbox(QGCToolbox *toolbox)
 #endif
 }
 
+void VideoManager::_videoSourceChanged(void)
+{
+    emit hasVideoChanged();
+    emit isGStreamerChanged();
+}
+
 //-----------------------------------------------------------------------------
 bool
 VideoManager::hasVideo()

src/FlightDisplay/VideoManager.h

@@ -67,11 +67,13 @@ signals:
     void isGStreamerChanged     ();
     void videoSourceIDChanged   ();
 
+private slots:
+    void _videoSourceChanged(void);
+
 private:
     void _updateTimer           ();
     void _updateVideo           ();
 
-private:
     VideoSurface*   _videoSurface;
     VideoReceiver*  _videoReceiver;
     bool            _videoRunning;