def send_video(self, chat_id, video, duration=None, caption=None, reply_to_message_id=None, reply_markup=None):
        """
            Use this method to send video files, Telegram clients support mp4 videos (other formats may be sent as
            Document). On success, the sent Message is returned. Bots can currently send video files of up to 50 MB
            in size, this limit may be changed in the future.
        """
        payload = dict(chat_id=chat_id,
                       duration=duration,
                       caption=caption,
                       reply_to_message_id=reply_to_message_id,
                       reply_markup=reply_markup)
        files = dict(video=open(video, 'rb'))
        return Message.from_api(api, **self._post('sendVideo', payload, files))