Can't say I have tried it, can't say I really plan to either. Not having a front facing camera is pretty killer to any video calling. Not too much of a point if you'r pointing your camera either at your feet or the sky, in which case either you can't see them or they can't see you.
If it meets your fancy though, give it a try and let us know how it turns out. I don't see why it wouldn't work unless it's spoecifically coded into the app to not work without a front facing camera.