diff --git a/frontend/src/components/ui/Modal.fullscreen.dom.test.tsx b/frontend/src/components/ui/Modal.fullscreen.dom.test.tsx
index ac0771fa..07d5b65c 100644
--- a/frontend/src/components/ui/Modal.fullscreen.dom.test.tsx
+++ b/frontend/src/components/ui/Modal.fullscreen.dom.test.tsx
@@ -106,3 +106,39 @@ describe("a dialog whose own content goes fullscreen", () => {
     expect(video.closest("body > div")).toBe(host);
   });
 });
+
+describe("Escape while the dialog's own content is fullscreen", () => {
+  const escape = () =>
+    act(() => {
+      window.dispatchEvent(new KeyboardEvent("keydown", { key: "Escape", bubbles: true }));
+    });
+
+  it("only leaves fullscreen (the browser's part) — the dialog stays open", () => {
+    // The browser spends that Escape on leaving fullscreen and still hands it to the page, with the
+    // video still the fullscreen element: the dialog closed with it, and the viewer lost the player.
+    const onClose = vi.fn();
+    render(
+      <Modal initialFocus="close" title="Player" onClose={onClose}>
+        <video aria-label="film" />
+      </Modal>,
+    );
+    setFullscreen(screen.getByLabelText("film"));
+    escape();
+    expect(onClose).not.toHaveBeenCalled();
+  });
+
+  it("still closes a dialog opened over something else that is fullscreen", () => {
+    const stage = document.createElement("div");
+    document.body.appendChild(stage);
+    setFullscreen(stage);
+    const onClose = vi.fn();
+    render(
+      <Modal initialFocus="close" title="Download" onClose={onClose}>
+        <p>form</p>
+      </Modal>,
+    );
+    escape();
+    expect(onClose).toHaveBeenCalledTimes(1);
+    stage.remove();
+  });
+});
diff --git a/frontend/src/components/ui/Modal.tsx b/frontend/src/components/ui/Modal.tsx
index d3babaf4..9f65bfec 100644
--- a/frontend/src/components/ui/Modal.tsx
+++ b/frontend/src/components/ui/Modal.tsx
@@ -13,7 +13,7 @@ import { useTranslation } from "react-i18next";
 import { X } from "lucide-react";
 import { useBackToClose } from "../../lib/history";
 import { anyBlockingLayerAbove, pushLayer, removeLayer, takeEscape } from "../../lib/layerStack";
-import { useFullscreenPortalHost } from "../../lib/fullscreen";
+import { fullscreenElement, useFullscreenPortalHost } from "../../lib/fullscreen";
 import { firstFieldIn, focusablesIn, trapTab, useDialogChrome } from "./dialogFocus";
 import { IconButton } from "./IconButton";
 import Toaster from "./Toaster";
@@ -151,7 +151,11 @@ export default function Modal({
     const onKey = (e: KeyboardEvent) => {
       if (takeEscape(e, id)) {
         e.stopPropagation();
-        close();
+        // The browser spends an Escape on leaving fullscreen and still hands it to the page, the
+        // fullscreen element still set. When that element is the dialog's own content (the library
+        // player's <video>), the Escape was the browser's: closing too lost the viewer the player.
+        const fs = fullscreenElement();
+        if (!(fs && rootRef.current?.contains(fs))) close();
         return;
       }
       // Focus trap: keep Tab / Shift+Tab cycling inside the dialog instead of reaching the inert