美妝品牌「佳麗粉黛」無法順利透過 Google 應用程式安裝廣告活動達到預期的觸及目標。他們想把重點放在影片素材資源上，將廣告素材組合調整到最佳狀態，該品牌目前的影片素材資源組合包含兩部直向影片和兩部橫向影片，片長介於 10 到 30 秒之間。請問這個影片素材資源組合中少了什麼？

The correct answer is a square video asset. Google App campaigns benefit from a diverse set of creative assets to maximize reach across various placements (e.g., YouTube, Google Play, Display Network). A square video (1:1 aspect ratio) is crucial for optimal performance on many platforms, especially social feeds, and is currently missing from the brand's portfolio. While longer videos (like a 60-second horizontal or vertical) can be beneficial, the immediate gap in aspect ratios is the square format. Carousel video assets are not a standard independent video asset type for App campaigns; rather, they refer to a format that can incorporate multiple images or videos.