If the "SS NITA" file is a fansub, MP4 is the logical choice. Older formats like AVI or MKV were common a decade ago, but MP4 offers native support for (the "SS" part) on most devices, including iPhones, smart TVs, and game consoles.
Tell me a bit more about the "Nita" you have in mind, and we can draft the piece together! SS NITA mp4