Video and image indexing

For video features Google needs an indexed watch page (ideally a dedicated page per video) with the video embedded, not hidden or loaded only after user actions, a supported file type and a valid thumbnail at a stable URL; metadata via VideoObject structured data, video sitemaps or Open Graph helps. Google does not index CSS images: use <img src>, descriptive filenames and alt text (which Google uses with computer vision and page content to understand the image), and image sitemaps for images it might not otherwise find.