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.
this is a proprietary format developed by Microsoft. Users have noticed low error resilience: sometimes insignificant damage to the file can cause the file not to play. Besides this, the closed format hampers its proliferation outside of Windows platforms.