VIV is a proprietary web audio/video streaming format used by the Vividas Player. The player, available for Win32, Mac OSX and Sun platforms, is distributed as native binary and installed on-demand via Java or ActiveX.
Developer blog: "Vividas is the company behind 'Vividas Player' (Suprise!) which is a video streaming platform (powered by VP6/VP7) which is very much like (to dumb things down) quicktime or Windows Media Player for streaming content, only with a twist. Its ultra fast, compact, installation-requiremente-requireded-no and very bandwidth efficient... The decoder - written in C/C++ with a healthy mix of ASM - is around 250-300Kb. Most of the internals is hush hush so I cant reveal much, but what is interesting is the uptake of broadband across the globe and the future prospects of HD-Quality video streaming and where this technology is headed" 
Actually the decoder is a 800kb DLL.
The player has support for Speex and Vorbis.
Layout of the file:
|1 byte||Length of name field|
|x bytes||Name field|
Extended company and product description is available on Wikipedia.