Think of it as your grandmother's form of graffiti. It's been called "yarn bombing" or "yarnstorming" - when you wake up to find your mail box or light pole has been covered in a colorful yarn sleeve, as if your grandmother had attacked it with a pair of knitting needles. Knitters around the world took up the prankster habit in the name of community beautification. The latest culprits in Las Vegas are a band of 80-year-old women. These seniors at the West Flamingo Senior Center call themselves "yarnstormers" and their latest creation is spicing up a once-drab overpass. We talk to them about what it takes to beautify a city, and how much work goes into crocheting a rainbow "cover" for an entire overpass.