If you want to show an image when the video ended. You can just put the image in front of the video box. And load it as collapsed (you can select it from the element properties panel).
And in your code expand the image when video is ended:
$w.onReady(() => {
$w("#video").onEnded(() => {
$w("#image").expand();
});
});
If there is a possibility that user can start the video again also add a code that will collapse the image when video is played.