I have also got the same problem, although with an even larger file. I made a file in Google Earth with high resolution image overlays of Egersund, a small town in Norway. The file size is 18 megabytes. I have tested this file on my computer so I know it works.
On my ADSL i have about 600 kbit of upload, and it takes around 4 minutes to complete so I know 18 megabytes of data has been uploaded. But then when I try to download it again from Google Earth Hacks, I just get a small file of a few kilobytes.
Obviously something is wrong with the scripts on this site?