chore: import upstream snapshot with attribution

utils/video.py

@@ -0,0 +1,44 @@
+import logging
+import requests
+from moviepy import VideoFileClip, concatenate_videoclips
+from utils.retry import download_retry
+
+
+@download_retry
+def download_video(url, save_path):
+    try:
+        logging.info(f"Downloading video from {url} to {save_path}")
+
+        response = requests.get(url, stream=True, timeout=(10, 300))
+        response.raise_for_status()  # 检查请求是否成功
+    
+        with open(save_path, 'wb') as f:
+            for chunk in response.iter_content(chunk_size=8192):
+                f.write(chunk)
+
+        logging.info(f"Video downloaded successfully to {save_path}")
+    
+    except Exception as e:
+        logging.error(f"Error downloading video: {e}")
+        raise e
+
+
+def concatenate_video_files(video_paths, output_path, codec="libx264", preset="medium"):
+    """Concatenate video files, releasing every ffmpeg reader even on failure.
+
+    Each VideoFileClip keeps an ffmpeg subprocess and file handle open until
+    closed; leaking them exhausts file descriptors on long multi-scene runs.
+    """
+    clips = []
+    final = None
+    try:
+        for path in video_paths:
+            clips.append(VideoFileClip(path))
+        final = concatenate_videoclips(clips)
+        final.write_videofile(output_path, codec=codec, preset=preset)
+    finally:
+        if final is not None:
+            final.close()
+        for clip in clips:
+            clip.close()
+    return output_path