I am not familiar with the TSW v6 Teensy upgrade, so I cannot be sure the steps listed are correct. The main point is that it will not work with the stock v6 firmware. You would need to upgrade to the TSW Teensy upgrade from the stock Nano. Fahran's video will work with WWV at 10 MHz. The tricky part is the confusion that the added tones and clock ticks create. It might take longer, however there are brief periods where the side tones are suppressed, and you can zero beat easier.
There are other benefits of the Teensy upgrade, especially if you plan to do mods to the program. There is no room or processor speed left in the stock Nano.
Above is my understanding of things that I do not have first-hand experience with. Use accordingly