Firefox FLV Cache

There are some tools for storing streaming video from youtube or other site like keepvid.com or flv plugins for firefox. But usually just use the manual way. I go to the firefox cache directory, see the latest and usually the largest file size. Copy it to other directory and give it an .flv extensions.

One thing that i don't understand, when I watch a rather long videos, usually the file in the cache would only store 25,584 KB of the file. This numbers is the same no matter what long video I cache. And what rather interest me is, when i see the video in my browser. It still replay able to its full length.

Today i Google some info, and i think i found the answer. First you can type about:cache in your firefox address bar. There you can see the Disk Cache Device information. It can show you how many entries in your cache, Maximum Storage Size, Storage in use, and a link to the cache directory.

Well one thing that i realize is, the size of 25,548. Is the size of half of the default Maximum Storage Size in firefox, which is 50 MB. So i tried to increase the Maximum Storage Size to 200 MB and refresh the video I'm watching, and finally able to get the full size video, which in my experiment is 29,418 KB.

I think firefox is limiting the size of a cache file into half of the maximum Disk Space. This because its almost imposible for a cache directory to only contains a single file. Almost all the time the directory will contains more than one file.

But that doesn't answer why i could re-play the full file in my browser ?

My guess is, it is stored in the memory. To prove it i try watch the firefox memory usage in windows task manager. And close the tab and reopen it again. The memory usage drop significantly, but not quite the same as the full size of the file. But i'm guessing that my hunch is correct.