diff --git a/group_video_man/bot_video_man.py b/group_video_man/bot_video_man.py
index 38462a6..072d2e8 100644
--- a/group_video_man/bot_video_man.py
+++ b/group_video_man/bot_video_man.py
@@ -45,7 +45,7 @@ class BotVideoMan:
                                (message.roomid if message.from_group() else message.sender), message.sender)
             return
 
-    def download_video(api_url, save_dir):
+    def download_video(self,api_url, save_dir):
         response = requests.get(api_url)
         if response.status_code == 200:
             data = response.json()