Official comment
The Ground Reference Image that gets recorded by the Map Pilot app at the time of landing should be uploaded at the same time as the rest of the images. You don't have to do anything special. We detect this image and look up the real elevation of the takeoff point to use as an offset.
http://support.dronesmadeeasy.com/hc/en-us/articles/206208583-Ground-Reference-Images
The youtube videos are getting pretty old at this point and need to be updated...