First, the roller goes over the screen and picks up any dust particles. That way when you go to wipe fingerprints and spots off the screen with a microfiber cloth (That would be step number two!), you're not scratching the screen.
And the TVClean people want you to know that you can use their product on any shiny surface, including glass and stainless steel. Does that make it worth the nearly $50 USD price tag? Only if you're obsessed with dust- and smudge-free surfaces. Otherwise, we might just stick with our Clorox wipes.