Designing reflective activities for online video learning could enhance learning outcomes and, to some extent, influence learning processes (ie, attentional processes and emotional experiences). It is necessary to select different levels of reflective activities in online video learning according to learning processes and outcomes. This study examined to what extent different levels of reflection may affect the learning outcomes, and further explored the impact of reflection on learning processes. Participants, comprising 60 undergraduates, were randomly and equally assigned to two different groups: a reflection group and a critical reflection group, and each group member completed specific learning tasks. The results of the learning outcomes showed that critical reflection led to better transfer performance than reflection, but retention performance was the same in both conditions. Regarding process measures, eye-tracking data indicated that the embedding of critical reflection strategies facilitated learners' visual attention, and controlled the difficulty of processing. Meanwhile, physiological data showed that the learners' reflection was accompanied by stress, and there was no significant difference between the two levels of reflection.