upload an image get media id and download it back using media id passed.

mediaId.go

 	//{"type":"TYPE","media_id":"MEDIA_ID","created_at":123456789}
 	var m = MediaID{}
 	json.Unmarshal([]byte(jstr), &m)
+	mediaid = m.MediaID
 	return
 }
 
 	}
 	return
 }
+
+func saveMedia2File(mediaID string) (filename string, err error) {
+
+	url := mediaID2URL(mediaID)
+	file, t, e := saveURL(url)
+	if e != nil {
+		return "", e
+	}
+	if t == "json" {
+		fmt.Println("get json should be video")
+	}
+	fmt.Println("save media to " + file)
+
+	return file, nil
+}
+
+func mediaID2URL(mediaID string) (url string) {
+	atk, _ := GetAccessToken()
+	url = fmt.Sprintf("https://api.weixin.qq.com/cgi-bin/media/get?access_token=%s&media_id=%s", atk, mediaID)
+	return
+}