Any FLV Player is a free multimedia player specialized in FLV video format, which play those kind of files without having to install extra codecs, just install any FLV plaver and you'll be able to watch your videos with no problem.
Its interface is very cool and you can personalize the colors easily. It includes basic functions like zoom, playlist, favorites,...
When you download videos from internet, most times they are FLV videos and you can't play them with your usual video player, so download any FLV player and enjoy them.
Any FLV Player also allows you to insert that kind of videos in your website.