You could try using Registax. Generally, Registax is used for astrophotography, particularly of the planets in our solar system. Registax uses the concept of superresolution to stack hundreds or thousands of frames, discard the worst, keep the best, then interpolate the information from all of those frames in such a way that it enhances detail and resolution.

While it is not specifically designed to do what you want, I see no reason why it couldn't be used for the purpose you are describing.

As an alternative, you could also use the median merge approach. Instead of using video and stacking to "photograph" low light scenes, just take about 10 still frames of the same scene (assuming no motion of anything within it) with the iPhone on a tripod of some kind. With Photoshop, you create a layer out of each of these still frames, select them all and convert to a smart object. Once you have a smart object, you set the stacking mode to median, which will GREATLY reduce the amount of noise in the scene without affecting detail.

Both solutions should work. The registax approach would be a little less manual work, however it might not produce as good a result as the manual stacking approach.