Short-video mobile apps are an emergent media form and play a significant role in young children's everyday lives. We explored the parental perspectives of 2-to-6-year-old Chinese children's use of short-video mobile apps. We distributed an online questionnaire that received 266 valid responses from parents and conducted in-depth interviews with 20 parents to understand children's usage and parents' attitudes, roles and mediations. Results revealed the most frequently watched genres were animated stories and reviews of toys. The affordances of short-video apps appeared to break children's normal media-use routine. Most parents acknowledged both the educational and intimate/family value as well as the psychological risks of short-video apps and tended to employ restrictive mediations to regulate children. We discuss different parental and children's attitudes towards using short-video apps. We also suggest parents initiating various mediated strategies according to dynamic contexts. We propose strategies for parents/caregivers, policy makers and technology designers for creating a vibrant and trustworthy media environment for young children.