If you're worried about your image not being added in the video, don't. The image will be rendered into the video once you've finished making the video. When you're in the editor you will only see thumbnails of your images, but once you finish making the videos it will fully replace the sample/background image. Of course, same applies for videos!

In the Video Editor, the images that you have imported are shown in small thumbnails as shown below:

Once the video editing and the rendering is complete, the image is fully replaced as shown below:

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