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diff --git a/testing/web-platform/tests/largest-contentful-paint/video-poster.html b/testing/web-platform/tests/largest-contentful-paint/video-poster.html
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index 0000000000..fdc691819b
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+++ b/testing/web-platform/tests/largest-contentful-paint/video-poster.html
@@ -0,0 +1,25 @@
+<!DOCTYPE HTML>
+<meta charset=utf-8>
+<title>Largest Contentful Paint: observe video poster image</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="resources/largest-contentful-paint-helpers.js"></script>
+<script>
+setup({"hide_test_state": true});
+async_test(function (t) {
+    assert_implements(window.LargestContentfulPaint, "LargestContentfulPaint is not implemented");
+  const beforeLoad = performance.now();
+  const observer = new PerformanceObserver(
+    t.step_func_done(function(entryList) {
+      assert_equals(entryList.getEntries().length, 1);
+      const entry = entryList.getEntries()[0];
+      const url = window.location.origin + '/images/blue.png';
+      // blue.png is 133 by 106.
+      const size = 133 * 106;
+      checkImage(entry, url, 'the_poster', size, beforeLoad);
+    })
+  );
+  observer.observe({type: 'largest-contentful-paint', buffered: true});
+}, "Able to observe a video's poster image.");
+</script>
+<video id='the_poster' src='/media/test.mp4' poster='/images/blue.png'/>