This seems to work well but I have run into downloads where it would fail and I would still have to use the built-in firefox downloader to retry the download. It doesn't have as polished an interface as "download status bar" or the convenience of "down them all" but since those extensions either don't work with FFQ or offer nothing more than cosmetic benefit, there are precious few choices besides this one. I suppose it may be speeding up downloads by a few seconds with the multi-threading, but this is a purely subjective and anecdotal observation that is not based on any actual speed measurements.