NSV (Nullsoft Streaming Video) is an audiovisual container format for streaming video data online. It was created in 2003 by Justin Frankel, while he was still working for Nullsoft. NSV only supports VP3 video codes and MP3 audio, although it was initially designed to stream all audio and video codecs. It is, in fact, the first format to allow users to make and stream live/recorded videos over the internet.
F4V is a filename extension for Flash Video (FLV) container format. It supports H.264 (MPEG-4 AVC) video codec compression standard, which is known to offer significant compression. FLV videos come in multiple formats apart from F4V, including F4P, F4A, and F4B. Also, it opens on Adobe Flash Player 6 or later and Windows Media Player.
Windows Media Player Adobe Flash Player 6 or later Media Monkey