My family, having had to deal with being the beta spectators for any new effect, has seen it all, almost literally. Practice Practice Practice - sometimes to their detriment. I prepared to give this one a shot after I learned the really easy method (FYI the instructions provided on how to run the effect without the gimmick were perfect, and I had no need for any of the additional devices) I performed this at the family first.
This is one of hte few times that I elicited actual screams, and explinations that ranged from - "You were doing the video as we watched it" to "Aliens"
This went instantly into my repertoire and I have performed it quite a few times - the fact that as long as they have a device that is connected to the internet is great - its readily available. Then to seal the deal, YOU NEVER TOUCH THE DEVICE - EVER. I will repeat it again, you NEVER TOUCH THEIR DEVICE!
Also the setup works well that you can A: repeat it, B: you can also do a setup to run for 2 spectators at the same time.
This is the perfect combination of Technology and Magic - the only thing I don't like is that I wish I had thought of it first.