Use gstqgcvideosinkbin's "sync" property to disable synchronization

src/VideoStreaming/VideoManager.cc

@@ -464,6 +464,8 @@ VideoManager::_makeVideoSink(gpointer widget)
 
     if ((sink = gst_element_factory_make("qgcvideosinkbin", nullptr)) != nullptr) {
         g_object_set(sink, "widget", widget, NULL);
+        // FIXME: AV: temporally disable sync due to MPEG2-TS sync issues
+        g_object_set(sink, "sync", FALSE, NULL);
     } else {
         qCritical() << "gst_element_factory_make('qgcvideosinkbin') failed";
     }

src/VideoStreaming/gstqgcvideosinkbin.c

@@ -128,9 +128,6 @@ _vsb_init(GstQgcVideoSinkBin *vsb)
             break;
         }
 
-        // FIXME: AV: temporally disable sync due to MPEG2-TS sync issues
-        g_object_set(vsb->qmlglsink, "sync", FALSE, NULL);
-
         if ((glcolorconvert = gst_element_factory_make("glcolorconvert", NULL)) == NULL) {
             GST_ERROR_OBJECT(vsb, "gst_element_factory_make('glcolorconvert' failed)");
             break;