That was an interesting series of qualitative tests she did. The results seem in line with the common experiences of friends who have damaged their smartphone screens -- scratching the screen is hard to do and the scratches tend to be barely visible, but cracking the screen is rather easy to do depending on how the phone lands and what it lands on when you drop it.
Take a glance around at people using their smartphones in a coffee shop or cafe some time. It's surprising how many have cracked but not completely shattered screens. The touchscreen continues to function, so it seems that many people just live with the cracks rather than pay for a repair.
Most people equate hardness with toughness. As any mechanical/materials science engineer will tell you they are two unrelated properties.
The most commonly used example is diamond. Now, diamond is the hardest naturally occurring material and it will resist scratching from anything softer. However, the same molecular structure that imparts this incredible harness, also make diamond relatively brittle. Diamonds have been known to shatter if dropped a few feet onto a hard surface. If you don't believe it, just try smashing your wife's (or your) wedding ring with a hammer and see what happens to the diamond.
A counter example is jade. The hardness of jade is somewhat lower that quartz (sand) but since it is made of a mesh of billions of nano fibers, it is tougher than steel. Jade "battle axes" have been found in archeological sites in South America. There is evidence that their use was not only ceremonial.
The chemical process used to make Gorilla Glass does improve both the toughness and hardness to some degree. Just don't expect Gorilla Glass to be indestructable.
It should be no surprise that Gorilla Glass can be scratched or shattered in normal use, it is only glass after all.
Those of us in the electronics industry may not be very aware of Corning's legacy of effective R&D and innovation. (I wasn't until reading a case study on them – Corning: 156 Years of Innovation – HBR 608108.) Even in modern times, they have maintained R&D spending in the face of recessions and focused on effective long-term product development over chasing short-term profits. Gorilla Glass is only one of their many success stories.
Corning's Gorilla glass was used in many other devices like Lab instruments, beakers, containers,etc, before making it to computing devices. In fact their glass is very well known in optic fibers which has high quality requirements.
This video is really good unlike some Promo Ad it shows the actual means of wear and tear and she puts it to some real abuse.
Girl's talking hi tech is hot too!