Yes, the 3 steps that are mandatory for this to work is completely safe. I have this on all my systems to reach them from !outside" and all people that use the NCS App on their smartphones as well.
However, if this is your first time maybe it is a good idea to google on this to find more information. On youtube there are videos for everything 
1.set up your computer with a static IP number.
2.setup your router to forward port 8080 for webcamXP to the static IP address obtained in 1.
3.find out the public IP address to your router.
When you have done these steps and you are not on wifi open the web browser in the cell phone. Enter http://publicIP:8080 now it should start.
-Henrik