In the diagram on the link they are using a three conductor cable after the first three way switch. Black, Red, and White with a separate ground.

Some of the most common cables you'll come across are red, yellow, and white. Sometimes, these cables come bundled together; ...

Run a 14-3 NM-B cable (white, black, red, bare copper) from your first switch to the second switch. Run a 14-2 NM-B cable from the second switch to the light fixture.

If you’re sick of playing your Nintendo Switch in regular HD, a man named Vince on YouTube has come up with a neat hack that lets you play on a tiny black-and-white Sony pocket TV instead.