diff --git a/src/css/injected.scss b/src/css/injected.scss
index 62a56537..9a92a4a3 100644
--- a/src/css/injected.scss
+++ b/src/css/injected.scss
@@ -3692,6 +3692,32 @@ div.day-empty {
   object-position: center;
 }
 
+.whatsnewHeader.bsCloudAutoSyncAnnouncementHeader {
+  height: auto;
+  min-height: unset;
+}
+.whatsnewHeader.bsCloudAutoSyncAnnouncementHeader h1 {
+  line-height: 1.2;
+}
+.bsCloudAccent {
+  color: #059669;
+  font-weight: 700;
+}
+.dark .bsCloudAccent {
+  color: #34d399;
+}
+.whatsnewTextContainer .bsCloudAutoSyncSignupCallout {
+  margin: 1.5rem 0 0;
+  padding: 1.25rem 1rem 0;
+  border-top: 1px solid color-mix(in srgb, var(--text-primary) 12%, transparent);
+  font-size: clamp(1.35rem, 3.8vw, 1.85rem);
+  font-weight: 800;
+  line-height: 1.35;
+  letter-spacing: -0.02em;
+  text-align: center;
+  color: var(--text-primary);
+}
+
 .popup-media-fullscreenable {
   cursor: pointer;
   transition: opacity 0.2s ease-in-out, transform 0.2s ease-in-out;
diff --git a/src/seqta/utils/Openers/OpenBsCloudAutoSyncAnnouncement.ts b/src/seqta/utils/Openers/OpenBsCloudAutoSyncAnnouncement.ts
new file mode 100644
index 00000000..440e3ca0
--- /dev/null
+++ b/src/seqta/utils/Openers/OpenBsCloudAutoSyncAnnouncement.ts
@@ -0,0 +1,71 @@
+import stringToHTML from "../stringToHTML";
+import { settingsState } from "../listeners/SettingsState";
+import { openPopup } from "./PopupManager";
+import { attachPopupMediaFullscreen } from "./attachPopupMediaFullscreen";
+
+/** Same hosting pattern as the What's New update video (GitHub raw). */
+const BS_CLOUD_DEMO_VIDEO_URL =
+  "https://raw.githubusercontent.com/BetterSEQTA/BetterSEQTA-Plus/main/src/resources/bsclouddemo.webm";
+
+export function shouldShowBsCloudAutoSyncAnnouncement(): boolean {
+  return !settingsState.bsCloudAutoSyncAnnouncementShown;
+}
+
+/**
+ * One-time announcement for BetterSEQTA Cloud automatic settings sync (after other startup popups).
+ * Video layout matches {@link OpenWhatsNewPopup} (`whatsnewImgContainer` / `whatsnewImg`).
+ */
+export function showBsCloudAutoSyncAnnouncement(onDismissed?: () => void) {
+  if (document.getElementById("whatsnewbk")) {
+    onDismissed?.();
+    return;
+  }
+  if (!shouldShowBsCloudAutoSyncAnnouncement()) {
+    onDismissed?.();
+    return;
+  }
+
+  const header = stringToHTML(
+    /* html */
+    `<div class="whatsnewHeader bsCloudAutoSyncAnnouncementHeader">
+      <h1>BetterSEQTA Cloud</h1>
+    </div>`,
+  ).firstChild as HTMLElement;
+
+  const imageContainer = document.createElement("div");
+  imageContainer.classList.add("whatsnewImgContainer");
+
+  const video = document.createElement("video");
+  const source = document.createElement("source");
+  source.setAttribute("src", BS_CLOUD_DEMO_VIDEO_URL);
+  source.setAttribute("type", "video/webm");
+  video.autoplay = true;
+  video.muted = true;
+  video.loop = true;
+  video.appendChild(source);
+  video.classList.add("whatsnewImg");
+  imageContainer.appendChild(video);
+  attachPopupMediaFullscreen(video);
+
+  const text = stringToHTML(/* html */ `
+    <div class="whatsnewTextContainer privacyStatement" style="height: 50%; overflow-y: auto; font-size: 1.2rem; line-height: 1.6;">
+      <p>
+        <strong class="bsCloudAccent">BetterSEQTA Cloud</strong> can keep your BetterSEQTA+ settings backed up and in
+        sync across browsers. Optional <strong>automatic settings sync</strong> runs when you are signed in (passwords
+        and tokens are never included).
+      </p>
+      <p>
+        Close this dialog when you are done. We will not show this announcement again.
+      </p>
+      <p class="bsCloudAutoSyncSignupCallout">Sign up in BetterSEQTA settings</p>
+    </div>
+  `).firstChild as HTMLElement;
+
+  settingsState.bsCloudAutoSyncAnnouncementShown = true;
+
+  openPopup({
+    header,
+    content: [imageContainer, text],
+    afterClose: onDismissed,
+  });
+}
diff --git a/src/seqta/utils/Openers/StartupPopupQueue.ts b/src/seqta/utils/Openers/StartupPopupQueue.ts
index b29b9e6c..3b05e88b 100644
--- a/src/seqta/utils/Openers/StartupPopupQueue.ts
+++ b/src/seqta/utils/Openers/StartupPopupQueue.ts
@@ -8,12 +8,17 @@ import {
   shouldShowEngageParentsAnnouncement,
   showEngageParentsAnnouncement,
 } from "./OpenEngageParentsAnnouncement";
+import {
+  shouldShowBsCloudAutoSyncAnnouncement,
+  showBsCloudAutoSyncAnnouncement,
+} from "./OpenBsCloudAutoSyncAnnouncement";
 
 type QueueStep = (goNext: () => void) => void;
 
 /**
  * Runs startup modals in order: What's New (if the extension just updated),
- * privacy statement (if required), then the SEQTA Engage announcement (once).
+ * privacy statement (if required), SEQTA Engage announcement (once), then BS Cloud
+ * auto-sync (once, last).
  */
 export function runStartupPopupQueue() {
   const steps: QueueStep[] = [];
@@ -30,6 +35,10 @@ export function runStartupPopupQueue() {
     steps.push((goNext) => showEngageParentsAnnouncement(goNext));
   }
 
+  if (shouldShowBsCloudAutoSyncAnnouncement()) {
+    steps.push((goNext) => showBsCloudAutoSyncAnnouncement(goNext));
+  }
+
   function runNext() {
     const step = steps.shift();
     if (step) step(runNext);
diff --git a/src/types/storage.ts b/src/types/storage.ts
index 5e72c618..adbaf8c9 100644
--- a/src/types/storage.ts
+++ b/src/types/storage.ts
@@ -34,6 +34,8 @@ export interface SettingsState {
   privacyStatementLastUpdated?: string;
   /** One-time announcement: SEQTA Engage support for parents (dismissed popup queue). */
   engageParentsAnnouncementShown?: boolean;
+  /** One-time announcement: BS Cloud automatic settings sync (last in startup popup queue). */
+  bsCloudAutoSyncAnnouncementShown?: boolean;
   timeFormat?: string;
   animations: boolean;
   defaultPage: string;