FLV (Flash Video) is a video container format developed by Adobe Systems and comes with a .flv filename format. FLV is primarily used to stream audio, video, and text data such as subtitles on sites like YouTube, Metacafe, and more. It supports MPEG-4 Part 10 (H.264) video codec and AAC sound.
RealPlayer, Apple QuicTime Player MPLayer VLC Media Player
OGV is a digital video container format related to the encoding technology of the OGG Vorbis video. It can save multiple related video stream codecs like the DivX and Theora. It is these codecs that allow OGV files to open on varying media players.
MPLayer Classic VLC Media Player Jriver Media Center MPUI