diff --git a/src/you_get/extractors/acfun.py b/src/you_get/extractors/acfun.py
index 983606d4..2ccc4718 100644
--- a/src/you_get/extractors/acfun.py
+++ b/src/you_get/extractors/acfun.py
@@ -17,10 +17,24 @@ def get_srt_json(id):
     return get_html(url)
 
 def acfun_download_by_vid(vid, title, output_dir='.', merge=True, info_only=False, **kwargs):
+    """str, str, str, bool, bool ->None
+    
+    Download Acfun video by vid.
+    
+    Call Acfun API, decide which site to use, and pass the job to its
+    extractor.
+    """
+
+    #first call the main parasing API
     info = json.loads(get_html('http://www.acfun.tv/video/getVideo.aspx?id=' + vid))
+
     sourceType = info['sourceType']
+
+    #decide sourceId to know which extractor to use
     if 'sourceId' in info: sourceId = info['sourceId']
     # danmakuId = info['danmakuId']
+
+    #call extractor decided by sourceId
     if sourceType == 'sina':
         sina_download_by_vid(sourceId, title, output_dir=output_dir, merge=merge, info_only=info_only)
     elif sourceType == 'youku':
@@ -32,11 +46,13 @@ def acfun_download_by_vid(vid, title, output_dir='.', merge=True, info_only=Fals
     elif sourceType == 'letv':
         letvcloud_download_by_vu(sourceId, '2d8c027396', title, output_dir=output_dir, merge=merge, info_only=info_only)
     elif sourceType == 'zhuzhan':
+        #As in Jul.28.2016, Acfun is using embsig to anti hotlink so we need to pass this
+        embsig =  info['encode']
         a = 'http://api.aixifan.com/plays/%s' % vid
         s = json.loads(get_content(a, headers={'deviceType': '2'}))
         if s['data']['source'] == "zhuzhan-youku":
             sourceId = s['data']['sourceId']
-            youku_open_download_by_vid(client_id='908a519d032263f8', vid=sourceId, title=title, output_dir=output_dir, merge=merge, info_only=info_only, **kwargs)
+            youku_open_download_by_vid(client_id='908a519d032263f8', vid=sourceId, title=title, output_dir=output_dir,merge=merge, info_only=info_only, embsig = embsig, **kwargs)
     else:
         raise NotImplementedError(sourceType)
 
diff --git a/src/you_get/extractors/youku.py b/src/you_get/extractors/youku.py
index 345347d0..853a75ba 100644
--- a/src/you_get/extractors/youku.py
+++ b/src/you_get/extractors/youku.py
@@ -330,22 +330,51 @@ class Youku(VideoExtractor):
 
     def open_download_by_vid(self, client_id, vid, **kwargs):
         """self, str, str, **kwargs->None
+        
+        Arguments:
+        client_id:        An ID per client. For now we only know Acfun's
+                          such ID.
+        
+        vid:              An video ID for each video, starts with "C".
+        
+        kwargs['embsig']: Youku COOP's anti hotlinking.
+                          For Acfun, an API call must be done to Acfun's
+                          server, or the "playsign" of the content of sign_url
+                          shall be empty.
+        
+        Misc:
         Override the original one with VideoExtractor.
-        Most of the credit are to @ERioK, who gave his POC."""
+        
+        Author:
+        Most of the credit are to @ERioK, who gave his POC.
+        
+        History:
+        Jul.28.2016 Youku COOP now have anti hotlinking via embsig. """
         self.f_code_1 = '10ehfkbv'  #can be retrived by running r.translate with the keys and the list e
         self.f_code_2 = 'msjv7h2b'
+        
+        # as in VideoExtractor
         self.url = None
         self.vid = vid
         self.name = "优酷开放平台 (Youku COOP)"
 
         #A little bit of work before self.prepare
-        sign_url = "https://api.youku.com/players/custom.json?client_id={client_id}&video_id={video_id}".format(client_id = client_id, video_id = vid)
+        
+        #Change as Jul.28.2016 Youku COOP updates its platform to add ant hotlinking
+        if kwargs['embsig']:
+            sign_url = "https://api.youku.com/players/custom.json?client_id={client_id}&video_id={video_id}&embsig={embsig}".format(client_id = client_id, video_id = vid, embsig = kwargs['embsig'])
+        else:
+            sign_url = "https://api.youku.com/players/custom.json?client_id={client_id}&video_id={video_id}".format(client_id = client_id, video_id = vid)
+
         playsign = json.loads(get_content(sign_url))['playsign']
-    
+
+        #to be injected and replace ct10 and 12
         api85_url = 'http://play.youku.com/partner/get.json?cid={client_id}&vid={vid}&ct=85&sign={playsign}'.format(client_id = client_id, vid = vid, playsign = playsign)
         api86_url = 'http://play.youku.com/partner/get.json?cid={client_id}&vid={vid}&ct=86&sign={playsign}'.format(client_id = client_id, vid = vid, playsign = playsign)
         
         self.prepare(api_url = api85_url, api12_url = api86_url, ctype = 86, **kwargs)
+        
+        #exact copy from original VideoExtractor
         if 'extractor_proxy' in kwargs and kwargs['extractor_proxy']:
             unset_proxy()