If you are running Windows, Linux or Raspberry Pi devices or using the Pre-Configured devices such as the Android stick.
You can remotely view what's actually playing on your devices by using the remote-control feature.
This is different than Preview feature, Preview will only play the content assigned to the devices on your PC, Remote Control feature will allow you actually remote to the device to view what it's playing there.
In Edit Screen Modal, under Advanced, there's Remote Control's Open button:
Clicking on it will open a new browser window for you to view and control the device.
To learn more about how to activate and use this feature click here.