No this is bunk.

The answer is directional freezing. Put the mold for the thing you want to be clear in a small cooler (or buy an insulated mold thing), be sure there is a hole in the bottom, fill it with water and put it in your deep freezer. Voilà clear ice for whatever purpose.

You don’t need to agitate it or boil it or use special water, just use physics and you’re all set.