Video: Guerrilla knitting hits Mexico

Magda Sayeg is tagging Mexico City and covering a bus in graffiti - only she's using knitting, not spray cans, to do the job. The 34-year-old Texan, founder of the guerrilla knitting collective KnittaPlease.com, faced her biggest challenge yet this week in Mexico City when she covered a whole bus in, well, knitting.