Willow Smith runs wild in the desert while shooting the music video for “21st Century Girl,” her follow-up single to “Whip My Hair,” which the pint-sized singer describes as a “dance record.” Over the weekend in Palmdale, Calif., the 10-year-old firecracker lit up the scene in a bright dandelion jacket and red skirt accented by a snaking yellow design, tied at the waist with a jewel-encrusted belt.