Upload a custom video preview image, also known as a poster or thumbnail, to control the appearance of videos in your gallery. This allows you to select a specific image that best represents your video content, ensuring that your gallery maintains a polished and professional look. By choosing a custom thumbnail, you can provide a clear and attractive preview that entices viewers to engage with your video. This enhancement offers greater flexibility in how your video content is presented, helping you to maintain consistent branding and visual appeal across all your galleries.