diff --git a/public/js/main.js b/public/js/main.js
index 6cc5792..216ff3e 100644
--- a/public/js/main.js
+++ b/public/js/main.js
@@ -899,6 +899,15 @@ document.addEventListener('DOMContentLoaded', () => {
         }
         resetPhases();
 
+        // Reset subtitle selector before subscribing to ensure we use the base key for source download
+        if (subtitleSelector) {
+            subtitleSelector.innerHTML = '<option value="-1">无字幕</option>';
+            subtitleSelector.value = "-1";
+        }
+        if (subtitlePanel) {
+            subtitlePanel.classList.add('hidden');
+        }
+
         selectedKey = key;
         currentVideoKey = key;
         subscribeToKey(key);
@@ -906,6 +915,12 @@ document.addEventListener('DOMContentLoaded', () => {
         nowPlaying.classList.remove('hidden');
         currentVideoTitle.textContent = key.split('/').pop();
 
+        // If download is needed, show the overlay so the user sees the progress
+        if (!hasDownloadCache) {
+            transcodingOverlay.classList.remove('hidden');
+            showDownloadPhase();
+        }
+
         // Fetch subtitle metadata
         fetchVideoMetadata(selectedBucket, key);
     };
diff --git a/server.js b/server.js
index 8c86b20..2b1a60e 100644
--- a/server.js
+++ b/server.js
@@ -192,12 +192,29 @@ const removeWsClient = (ws) => {
 };
 
 const broadcastWs = (key, payload) => {
+    // Broadcast to the specific room
     const clients = wsSubscriptions.get(key);
-    if (!clients) return;
     const message = JSON.stringify(payload);
-    for (const client of clients) {
-        if (client.readyState === WebSocket.OPEN) {
-            client.send(message);
+    if (clients) {
+        for (const client of clients) {
+            if (client.readyState === WebSocket.OPEN) {
+                client.send(message);
+            }
+        }
+    }
+
+    // If this is a base key (not a sub-key), also broadcast to all its sub-keys
+    if (!key.includes('-sub')) {
+        for (const [subKey, subClients] of wsSubscriptions.entries()) {
+            if (subKey.startsWith(`${key}-sub`)) {
+                for (const client of subClients) {
+                    if (client.readyState === WebSocket.OPEN) {
+                        // We need to keep the payload key matching the room key for filtering on the client side
+                        const subPayload = { ...payload, key: subKey };
+                        client.send(JSON.stringify(subPayload));
+                    }
+                }
+            }
         }
     }
 };