It's just showing you how to use the tilt sensor.
After an hour has passed and all of the lights are turned on you are supposed to turn it upside down just like a real hour glass. That will cause the project to reset.
Tilt sensors could be useful. If you have a new smart phone you will notice the screen probably changes based on if you are holding the phone vertically or horizontally. You could probably do that with a tilt sensor of some kind.