Surface real screenshot DownloadError detail

app.py

@@ -287,9 +287,8 @@ def run_pipeline(topic, hf_token, yt_api_key, llm_model, vlm_model,
                 selected = frames_mod.capture_shots(
                     times, best["video_id"], frames_dir, cookiefile, proxy, progress)
             except Exception as exc:
-                yield (status(f"⚠️ Couldn't fetch screenshots ({type(exc).__name__}) — "
-                              "producing a **text-only** tutorial. Ensure `YT_PROXY` is set "
-                              "(HTTPS proxy) so yt-dlp can download clips."),
+                yield (status(f"⚠️ Couldn't fetch screenshots — text-only tutorial. "
+                              f"`{type(exc).__name__}: {str(exc)[:400]}`"),
                        ranking, gr.update(value=transcript), gr.update())
             if selected:
                 progress(0.88, desc="Captioning")