I don’t know what you mean by use Asus DDNS for your CCTV; the Asus DDNS is an excellent and reliable way of representing your public IP address and must be by far the easiest way to set up DDNS on your router.
Try it, it’ll probably take longer to log into your router than it will to set up your asuscomm.com DDNS address. If it doesn’t do what you intended, ditch it, nothing lost.