I've added two videos that are a little long, but worth watching. First is a video from Fox 13 News at Nine. We hear from different taggers in Salt Lake City about their reasons for tagging. The video also includes how some kids are learning how to tag legally.
Second, a video made for the CSUN's MOSAIC program. It shows graffiti artists, including youths working to promote graffiti as a legit art form. Also depicted in this video is a group that's known as "Walls to Canvas."