DevConverter converts your video files online. Amongst many others, we support MP4, WEBM and AVI. You can use the options to control video resolution, quality and file size.
FLV is a Flash compatible video container that is used in several online video and audio streaming sites. Although it is viewed in web browser using adobe flash player, many other players also support FLV files. It has a header. It follows the similar format that a flash extension (.swf) uses to store video and audio data.