The performer holds three envelopes, each of a different colour (say Red, Yellow and Blue). First he designates two helpers as 'the person on my left' and the 'person on my right'. This is important so that later there will be no confusion between the performer's left and right and the audience's.
Each of the two helpers choose one of the envelopes, leaving the performer with one. Emphasis is placed again by pointing out that 'the lady on my left has chosen the Blue (or whatever it was), and the lady on my right has chosen the Yellow (for example)'. They are then asked to open their envelopes and read out the predictions contained therein. The person on the left reads 'I predict that you will choose the Blue envelope' and the person on the right reads that she will choose the Yellow envelope.
Indignant at the horse laugh this will get from the audience (although I have seen some people do a double-take before it dawns on them), the performer opens his envelope and hands the contents to someone to read aloud. It says 'I predict that I will be left with the Red envelope, that the person on my left will choose the Blue, and the person on my right the Yellow'.
Don't confuse with Technicolor Prediction by Ed Marlo explained in Ireland's Yearbook 1962, page 64.