Unfortunately the example project from NormalMapExtended doesn't account for scrolling. However that doesn't meant that the effect isn't working, it just means that you will have to adapt your code to keep light position at bay.
I would recommend using my improved version of the NormalMapExtended addon called "NormalMap32". It is in every aspect a little better than NormalMapExtended, is also better documented, and the example project accounts for your mentioned issue.
Already switched, and it works immediately. Spent around 6 hours trying to get the Extended version to work, and it always seemed off, so I'm guessing it's just buggy.