Use of flipped learning environments, where content is delivered online outside of class and class time features student-centered activities, is an increasingly popular way to facilitate active learning. The success of classroom activities, however, depends on students' willingness to complete the out-of-class work and come to class well prepared. Therefore, it is important for instructors to understand students' attitudes towards required pre-class preparation. This study used an online questionnaire, featuring both Likert-type and open-ended questions, to explore students' attitudes towards the online video used in a flipped undergraduate science class. Results showed moderately positive attitudes toward the pre-class video lecture, but also some strongly negative attitudes. Results of this study can help instructors understand both the benefits of flipped learning from the student perspective and the likely sources of resistance. This understanding can help instructors anticipate students' concerns and provide effective orientation when introducing the flipped learning model in undergraduate courses.