RED5

FLV (Flash Video) is a proprietary file format used to transmit video over the Internet using Adobe Flash Player (formerly known as Macromedia Flash Player), from version 6 to 10. FLV content can be embedded within SWF files. Among the most notable sites that use FLV format include YouTube, Google Video, Reuters.com, Yahoo! Video and MySpace.
 
Flash Video can be seen on most operating systems, using Adobe Flash Player plugin widely available to Web browsers, or other third-party programs such as MPlayer, VLC media player or any player that uses DirectShow filters (such as Media Player Classic, Windows Media Player and Windows Media Center) when the filter is installed ffdshow.