While previous studies have focused on the outcomes of using dubbing apps to foster learner's development of English-speaking ability, this study, grounded in cognitive apprenticeship (CA), is an investigation of the learning processes, which included modeling, coaching, scaffolding, articulation, reflection, and exploration, involved in the use of a dubbing app, Mofunshow. Participants included 26 college students at a science and technology university in Taiwan. Data included GEPT speaking pre-and post-test scores, initial and final dubbing videos, learning logs, and reflective essays. The results showed that after engaging in video dubbing the students improved their English-speaking ability, in terms of accuracy and fluency. Coaching and modeling were ranked as the two most useful processes which supported students as they improved their English-speaking ability through repeatedly listening, echoing, and imitating. Implications and limitations of the study are discussed.