Yee-haw! The lucky son of a gun who won the Firefly Gag-Reel got it encoded and uploaded, and it's available at www.fireflyfans.net. Try one of the mirror sites linked at the bottom of the page, to save on their bandwidth.
If you can't play a big mp4 file, or you can't get it to download, email me about getting the Gag Reels in 4 files, QuickTime .mov format. (firstname.lastname@example.org)