A simple scam. You get a taxi in a country you’ve not visited before. You hand over your money to pay, but the taxi driver hands you back your note explaining it’s a fake note and you must give another.
You do and presume you got ripped off from the company you got your currency from but actually the taxi driver using slight of hand has switched his fake note (that he purchased early for 50% less) with your real one. So he pockets the profit + an extra 50%.
We guess the only way to stop this is by quickly photographing your notes before you hand them to the driver (as done in the video), or maybe draw a shape in the corner and show them it as you hand it to them.