Either one should be fine. Of course the laptop with quad core i5 / i7 CPU and the GTX 950m + 4GB VRAM will provide better performance. However, the one with dual core i5 / i7 and the GTX 950m + 2GB VRAM is capable enough of doing video and photo editing. After all, a lot of people use MacBook Pros for the exact same thing and they only have dual core CPUs and integrated graphics. It think it was only recently with the 2017 MacBook Pros that Apple started to use quad core CPUs. If performance matters a lot to you then get the higher end Asus. If you are budget conscience, then get the lower end Asus.
The GTX 950m is not powerful enough to make use of more than 2GB of VRAM for RAM in games. You would typically need more than 2GB of VRAM if you want to play games at ultra high settings which the GTX 950m is not powerful enough to do so. CUDA cores in nVidia GPUs can be used to improve video editing performance as long as the software used can take advantage of CUDA cores. Do not not believe the amount of VRAM has any significant effect on performance.
However, photo editing can eat up at lot of system RAM depending on the size of the project and number of filters / effects you are using. Therefore, you should shoot for at least 16GB of RM.