most likely dumaan yan sa ddns since there is no way to view the DVR via local IP if you are not from the same local network. local network = local IP, external network = external IP. since there is no way to specifically point what the external IP of smartbro is (i.e. dynamic IP), the other option would be to setup a ddns service so even if the external IP changes, all you need to type in is the host name and it will still connect to the DVR
ddns service will give you a host name (lets say myhouse.net), now with the DDNS, instead of typing in the external IP and the port used (i.e. 221.254.125:8880), all you need to type in is myhouse.net. this will save you time from figuring out what your external IP is and the more important part is the port forwarding since you will basically be using http (i.e. port 80, 8080) there should be no problem with port forwarding anymore.
bottomline smartbro does not give you the option to port forward and it uses dynamic IP so you will need something like a dynamic DNS service for remote viewing