An existing Hero block on an AEM Edge Delivery Services site currently shows a full-width background image with overlaid headline and CTA. The client wants to add a new video variant that replaces the background image with an autoplaying, muted, looping background video. On mobile, the video should fall back to a poster image for performance. The text overlay and CTA should remain identical to the image variant.
Analyze this variant addition and produce structured acceptance criteria. Do NOT write any code.