When Google announced Android N Developer Preview, you could see how they wanted to ensure that the final release to the masses is bug-free and therefore take in and solve all the bugs that are reported. Apple was the first to the game, where it has been releasing the Public Beta of its Operating Systems for a while in order to garner public opinion on the same. Therefore, if you are one of those that have decided to flash Android N on your Nexus phone and are an ardent watcher of Netflix, we know you are facing a problem.
Several Netflix users with Android N are complaining that it is occurring that when you go on to play any video, only the audio is being heard while there is nothing on the screen, other than a black dark blank window. This behavior could also have been occurring with other apps that play videos such as Vimeo. The solution, most likely to the problem is to disable the Night Mode on your phone and try again. It should work without a hitch. In case you have applied any sort of colour correction on your display, you should disable the same too, for the video to play properly.
According to a Reddit thread about the same problem, it could be a DRM maneuver by Netflix to ensure that there is no sort of screen recording that is happening to take the content away. We hope that Google will fix the problem when the final release of Android N comes, till then, you will have to watch Netflix without any Night Mode on.