Based on joint media engagement (JME) and parental mediation theory (PMT), this study conducted a textual and thematic analysis of 360 user-generated content videos to explore, in the family scenario, smart speaker use behavior between Chinese children and parents. The findings reveal the following: (a) smart speakers create a new JME model and new co-use scenarios; (b) the mediation strategy used by parents differs from the mediation strategies in traditional PMT; (c) smart speakers are social actors and play a mediating role in the construction of family relationships; and (d) smart speaker use behavior between parents and children is characterized by a return to the living room era, which creates a new family dynamic and a reshaping of family politics.