fix

typescript/frontend-marios2/src/components/DocumentList.tsx

@@ -136,13 +136,19 @@ function DocumentList({
     });
   }, [documents]);
 
-  // Clean up blob URLs on unmount
+  // Revoke superseded blob URLs as state changes, and on unmount.
+  // Empty deps would capture the initial {} and never revoke anything.
   useEffect(() => {
     return () => {
       Object.values(previews).forEach((url) => window.URL.revokeObjectURL(url));
+    };
+  }, [previews]);
+
+  useEffect(() => {
+    return () => {
       Object.values(videoUrls).forEach((url) => window.URL.revokeObjectURL(url));
     };
-  }, []);
+  }, [videoUrls]);
 
   const handleDownload = (doc: DocumentItem) => {
     const cached = previews[doc.id] || videoUrls[doc.id];