GVRRendererViewController *viewController = self.childViewControllers[0];
  GVRSceneRenderer *sceneRenderer = (GVRSceneRenderer *)viewController.rendererView.renderer;
  GVRVideoRenderer *videoRenderer = [sceneRenderer.renderList objectAtIndex:0];

if let vc = self.children.first as? GVRRendererViewController {
                self.vrManager!.setupGVR(vc)
            }

func setupGVR(_ gvrRendererVC: GVRRendererViewController) {
        let sceneRenderer = gvrRendererVC.rendererView.renderer as! GVRSceneRenderer

        if sceneRenderer.renderList.count() > 0,
            let videoRenderer = sceneRenderer.renderList.object(at: 0) as? GVRVideoRenderer {
            videoRenderer.player = self.avPlayer
        }
    }