From the video description:
In this video we show a couple of ways to test your edge after sharpening using your thumbnail. These tests are geared mostly towards kitchen knives, but may sometime be applicable elsewhere.

As i mention in the video, there are not the end-all-be-all of tests, but they do provide useful feedback and can help you asses your sharpening work quickly and easily.

If you have any questions, please feel free to contact us at Jon@JapaneseKnifeImports.com or look us up at www.JapaneseKnifeImports.com

Thanks.

-Japanese Knife Imports