A face can communicate a reaction or establish a recognizable presenter, but it should not consume the space needed to explain the video. Start with the subject, then decide what the person contributes.
Define the face's role
Is the presenter demonstrating, reacting, or simply identifying the series? Use a frame that matches that role. An exaggerated expression can feel disconnected when the video is a calm technical explanation.
Protect the useful detail
Position the face so it does not cover the product, result, or critical hand movement. If both face and object become tiny, simplify the layout or choose a closer frame instead of squeezing everything into one image.
Check the relationship
Make sure the person's gaze and gesture lead toward something meaningful within the composition. Review the image without the title: does it communicate a believable scene? Keep the reaction proportionate to what viewers will actually see so the packaging and video feel consistent.