The idea of the magnet is that it will hold back the rotating dial from advancing as electricity is consumed. The video you showed has been floating around for a very long time but it doesn't actually show you what I explained above.
In his video he simply had some magnets stuck to the side of the meter. That wouldn't have done anything to the meter at all and have to agree with the guy in the video Oncor was off base and out of line.
Most of the meters today are "smart" meters measuring actual voltage and current. They no longer use the disk rotated by eddy currents. But even if you still have the old meter, don't experiment and stay out of jail.