Patricia G. Lange, Kids on YouTube: Technical Identities and Digital Literacies, Walnut Creek, CA: Left Coast Press, 272 pp., $34.95 (paperback). Nowadays, social media is inundated with videos of children and families, depicting everything from seven year olds' birthday parties to high school graduations to a toddler bouncing on an inflatable mattress. In this video-rich environment, it is …