Well, I guess you can view the video footage from local network. That means you need to do the portforward in your router or DVR.
After doing the port forward, you need to type the WAN IP address with port to visit the DVR. If you don't know your internet address, you can google "What's my ip?"
For the DDNS, you need to either use the manufacturer's default DNNS service or the no-ip.com free DDNS service.
More information, you can read this article:
http://www.hkvstar.com/technology-ne...ork-setup.html