FLV (Flash Video) is a proprietary file format used to deliver video over the Internet via Adobe Flash Player (formerly known as Macromedia Flash Player) version 6, 7, 8, or 9. Recently a number of notable Websites, such as Youtube, Google video and Reuters, use FLV format.If you don't want your video to be watermarked by Youtube or other video hosting website, you should convert your video yourself, and host the converted FLV video yourself.