The concept is great in a perfect setting. Your own phone must be used and placed just perfectly in
great lighting. You must write the "prediction" in all caps with almost exact penmanship.
Unless you are a stage performer this will be difficult to do on the fly. The outcome is not
100% it will give you false information often and when that happens you have no way out (that I know
of).
I wish it would have worked but I am an impromptu performer and this is just too
unreliable for me. I am sorry to say that I have never been able to use this trick.