Charging $10 for access to a very simple concept. Another example of the trailer being cut in ways
that you don't see the whole trick, or one might have guessed how to do this. The video explanation
is just under 1 hour long, but doesn't need to be - a higher-quality, 5 minute video would suffice.
No need to pay for this trick, folks - you'll find similar method explanations cheaper (or free!)
elsewhere.