The vivo format is a realtively new proprietary format that has two main advantages:
It compresses video and sound at very high ratios.
You can stream vivo video over regular 33.6 kbps connections without having to set up special streaming servers.
The Vivo Format is different to Real Video or Windows Media as the video stream is always sent using HTTP. In the Spring of 1998, Real Networks purchased Vivo but they said they will continue to support it. As if.