Fix: Ensure video display overwrite on regeneration

Problem 1: Videos not overwritten when regenerating
- Previous videos remained visible even after new generation
- Users confused whether they're seeing old or new videos

Problem 2: Partial success handling unclear
- When some models fail, unclear which videos are new
- Score sliders showed for all models regardless of success

Solution:
1. Always update HTML content (success OR failure)
- Success: Show video with green border and model name
- Failure: Show warning message with orange border
- Both cases explicitly set value, ensuring overwrite

2. Individual score slider visibility per model
- Before: Used global has_results (all or nothing)
- After: Each model's slider shows only if that model succeeded

3. Visual distinction with color-coded borders
- Green (#4CAF50): Successful generation ✅
- Orange (#ff9800): Failed generation ⚠️
- Includes model name in display for clarity

Benefits:
- ✅ Every generation completely overwrites previous display
- ✅ Clear visual feedback for success/failure per model
- ✅ Score sliders only appear for successful models
- ✅ No confusion about which videos are current
- ✅ Better UX with color coding and model names

Testing: Verified with test_overwrite.py simulation

app.py

@@ -782,10 +782,13 @@ with gr.Blocks(title="Video Model Evaluator") as demo:
         for model_name in MODELS_TO_CALL:
             video_value = urls.get(model_name, None)
             # 返回视频组件更新（使用HTML video标签避免卡顿）
+            # 重要：每次都要明确设置value，确保覆盖之前的内容
             if video_value:
                 # 使用HTML video标签，更可控且不会卡顿
+                display_name = MODEL_DISPLAY_NAMES.get(model_name, model_name)
                 video_html = f"""
-                <div style="margin: 10px 0;">
+                <div style="margin: 10px 0; padding: 15px; border: 2px solid #4CAF50; border-radius: 10px; background: #f1f8f4;">
+                    <h4 style="margin-top: 0; color: #4CAF50;">✅ {display_name}</h4>
                     <video controls style="width: 100%; max-width: 640px; border-radius: 8px;">
                         <source src="{video_value}" type="video/mp4">
                         Your browser does not support the video tag.
@@ -801,10 +804,20 @@ with gr.Blocks(title="Video Model Evaluator") as demo:
                 </div>
                 """
                 outputs.append(gr.update(value=video_html, visible=True))
+                # 该模型成功，显示评分滑块
+                outputs.append(gr.update(visible=True))
             else:
-                outputs.append(gr.update(value="", visible=False))
-            # 评分滑块可见性
-            outputs.append(gr.update(visible=has_results))
+                # 该模型失败或未生成，清空并隐藏
+                display_name = MODEL_DISPLAY_NAMES.get(model_name, model_name)
+                failed_html = f"""
+                <div style="margin: 10px 0; padding: 15px; border: 2px solid #ff9800; border-radius: 10px; background: #fff3e0;">
+                    <h4 style="margin-top: 0; color: #ff9800;">⚠️ {display_name}</h4>
+                    <p style="color: #666;">视频生成失败或未完成</p>
+                </div>
+                """
+                outputs.append(gr.update(value=failed_html, visible=True))
+                # 该模型失败，隐藏评分滑块
+                outputs.append(gr.update(visible=False))
         
         # 添加提交按钮可见性、状态变量
         outputs.extend([