Just a heads up: your complete browsing history is stored on your computer no matter what. You can delete the history that Firefox stores, however, your computer will store another copy for legal purposes and it cannot be removed. ---- This file is related to the [https://addons.mozilla.org/en-US/firefox/addon/flash-video-downloader/ Flash Video Downloader] extension that you must have installed on Firefox currently or at some time. I cannot say for certain what the extension is using this data for or why it is storing it. You would need to contact the extension developer for this information.