Given their easy accessibility and dual-channel model of content presentation, instructional videos have become a favoured tool for EFL vocabulary learning tool among many students. Teachers often use various nonverbal behaviours to elicit social reactions and guide learners' attention in instructional videos. The current study conducted three eye-tracking experiments to examine the circumstances under which a teacher's happy facial expressions are beneficial in instructional videos, with or without pointing gestures and mouse pointing. Experiments 1 and 2 demonstrated that the combination of happy facial expressions and pointing gestures attracted learners' attention to the teacher and hindered students' learning performance, regardless of the complexity of slides. Experiment 3 showed that in instructional videos with complex slides, using happy facial expressions along with mouse pointing can enhance students' learning performance. Teachers are advised to show happy facial expressions and avoid using pointing gestures when designing instructional videos.