https://developers.weixin.qq.com/doc/offiaccount/Message_Management/Service_Center_messages.html

{
    "touser":"OPENID",
    "msgtype":"video",
    "video":
    {
      "media_id":"MEDIA_ID",
      "thumb_media_id":"MEDIA_ID",
      "title":"TITLE",
      "description":"DESCRIPTION"
    }
}