There are two different video file formats known as Flash Video: FLV and F4V. The audio and video data within FLV files are encoded in the same manner as they are within SWF files. The F4V file format is based on the ISO base media file formatand is starting with Flash Player 9 update 3.
As opposed to the more common RealMedia container, which holds streaming media encoded at a constant bitrate (CBR), RMVB is typically used for multimedia content stored locally. Files using this format have the file extension .rmvb.