Video dubbing is a new type of language learning practice. Because of the fun it brings into learning, video dubbing mobile applications have become quite popular. During video dubbing, learners not only mimic characters' pronunciations but also other voicing characteristics, e.g., emotions. In this study, we collected a corpus from Liulishuo English learning App's video dubbing practices and investigated three research questions. We find that L2 learners do try to mimic emotions via their voices, and human raters tend to focus more on the emotion production aspect when evaluating dubbing performance. Furthermore, we develop state-of-the-art speech emotion recognition technology and show it can be used for evaluating emotion production automatically.