My firefox cache is set to 500mb, since I have a persistent home and I was hoping /tmp wouldn't be used. But as Jason and jpeters said, that doesn't keep flash from storing the file in /tmp. I've actually started using /tmp as a source for saving flash-based video files rather than using the DownloadHelper firefox extension, since it is more consistent. It asks the question, though, of why Flash is still the prefered method of delivering online video. Not only is Flash very heavy on the processor, but it apparently uses up to twice as much temp space as it really needs.