Flash Video is a container file format used to deliver video over the
Internet using Adobe Flash Player (initially produced by Macromedia) versions
6–10. Flash Video content may also be embedded within SWF files. There are two
different video file formats defined by Adobe Systems and supported in Adobe
Flash Player: FLV and F4V. The audio and video data within FLV files are encoded
in the same way as they are within SWF files. The latter F4V file format is
based on the ISO base media file format and is supported starting with Flash
Player 9 update 3.[1][2]
The format has quickly established itself as the format of choice for embedded
video on the web. Notable users of the Flash Video format include YouTube,
Google Video, Yahoo! Video, metacafe, Reuters.com, and many other news
providers.
The standards documentation for BBC Online states that the BBC now
preferentially accepts Flash videos for submission, to the disadvantage of other
formats previously in use on its sites[3] such as RealVideo or WMV.
Though the Flash Video container format itself is published, most of the
compression formats used with it are patented. Flash Video FLV files usually
contain material encoded with codecs following the Sorenson Spark or VP6 video
compression formats. The most recent public releases of Flash Player also
support H.264 video and HE-AAC audio.
Flash Video is viewable on most operating systems, via the widely available
Adobe Flash Player and web browser plugin, or one of several third-party
programs.