Video-based learning (VBL) is popular, yet students tend to learn video material passively. Instilling teaching expectancy is a strategy to promote active processing by learners, but it is unclear how effective it will be in improving VBL. This study examined the role of teaching expectancy on VBL by comparing the learning outcomes and metacognitive monitoring of 94 learners with different expectancies (teaching, test or no expectancy). Results showed that the teaching expectancy group had better learning outcomes and no significant difference in the metacognitive monitoring of three groups. We further explored the visual behaviour patterns of learners with different expectancies by using the indicator of eye-movement synchronization. It was found that synchronization was significantly lower in both the teaching and test expectancy groups than in the no expectancy group, and the test expectancy group was significantly lower than the teaching expectancy group. This result suggests that both teaching and test expectancy enhance the active processing of VBL. However, by sliding window analysis, we found that the teaching expectancy group used a flexible and planned attention allocation. Our findings confirmed the effectiveness of teaching expectancy in VBL. Also, this study provided evidence for the applicability of eye-tracking techniques to assess VBL.