Educators can use video to gain invaluable information about their students. A concern is that collecting videos online can create an increased security risk for children. The purpose of this article is to provide ethical and legal guidelines for designing video-based apps for mobile devices and the web. By reviewing the literature, law, and code of ethics around designing sites that capture video of young children, we have developed a set of questions that can guide designers through the decisions that need to be considered in their plans. As an example, we describe how we applied these questions to the design of a "Story Retell" app, which enables students to share videos of themselves reading to gain feedback from their teachers. Although each design decision will vary across instructional contexts, these guidelines can serve as a framework for designing similar apps that collect video of children.