Why a video can make you feel you understood more than you did
Explainer videos are engaging and easy to follow, and that fluency is part of the problem. Watching one can leave learners overestimating how much they actually grasp, a gap between felt and real understanding that researchers call an illusion of understanding [1]. The video feels smooth, so the mind treats smoothness as a signal of mastery.
That illusion is not evenly distributed. In the physics-video experiments, learners who came in with less prior knowledge about the topic were more prone to overestimating their understanding [1]. This fits a simple intuition: the less you know, the harder it is to notice what you are missing, so the video's confident narration fills the gap.
What a follow-up task actually changes
Adding a cognitively demanding task after the video measurably shrank the illusion. In one experiment with 244 learners, high-level tasks reduced overestimation of understanding immediately after the intervention compared with watching the video alone, a moderate-sized effect [1]. The task appears to force learners to test their grasp rather than merely recognize familiar material.
The task's difficulty mattered for the immediate effect but not for the long run. A second experiment with 175 learners found that over the longer term, high-level and low-level tasks were similarly effective [1]. So the demanding version gives a quicker correction, while even a simpler task seems enough to keep the illusion in check over time.
Prompt-questions help, but not for the reason you might guess
A separate study with 133 teacher and psychology students tested prompt-questions placed after an explainer video, followed by learning from a text. Watching the video made the content seem more interesting and less difficult, yet learners underestimated rather than overestimated themselves, which runs against the illusion-of-understanding expectation [2]. With prompt-questions, the video group learned better from the subsequent text; without them, the video's advantage did not appear.
The interesting part is why. Exploratory analyses suggested the video's advantage in the prompt condition was driven mainly by the quality of learners' answers, not by how much time they spent answering [2]. That points to something more like genuine processing than extra effort, though the authors describe this as exploratory and call for replication under more controlled conditions.
So should you add tasks after a video?
The practical takeaway is that explainer videos work better as a starting point than as a standalone lesson. The physics-video authors conclude that videos should not be used in isolation in science classrooms, and that pairing them with cognitively demanding follow-up activities helps prevent misjudged understanding, especially for students with limited prior knowledge [1].
One caution about scope: the prompt-question study found that the same prompts that helped after a video actually impaired learning in a video-script condition [2]. The benefit is tied to the combination of medium and task, not to tasks in general. And the evidence on lasting understanding comes from short-term and follow-up experiments in specific settings, so the size of the long-term gain outside those contexts is not settled [1][2].
Sources used in this answer
Learning Science and the Illusion of Understanding: Exploring the Effects of Integrating Learning Tasks after Explainer Videos
High-level learning tasks after a physics explainer video significantly reduced learners' illusion of understanding immediately, and over the long term both high- and low-level tasks were similarly effective, with lower prior knowledge increasing susceptibility to the illusion.
Does watching an explainer video help learning with subsequent text? – Only when prompt-questions are provided
Prompt-questions after an explainer video fostered subsequent text learning, driven mainly by the quality of prompt-answers rather than time invested, while the video made content seem more interesting and less difficult without causing overestimation.
Enhancing EFL oral proficiency through video-based tasks implemented in a flipped classroom
Video-based tasks in a flipped classroom were associated with improved EFL speaking fluency and accuracy and increased confidence, without explicitly distinguishing lasting understanding from a feeling of comprehension.