muvee Reveal makes a muvee using photos and videos in order. When it plays a muvee, each photo or video in the media panel is highlighted as it appears in the muvee.
By changing the order, you can control when your photo will appear, so that you can time it to match your song. You can also click any photo and click Mode on its context menu to change how long it is shown for. This can help you control when your photo appears.