Many a times, you would have noticed that Megaupload blocks file downloads for some countries on an hourly basis.
Firefoxpro.net has a freeware Firefox extension for Megaupload upload/download service that allows you to bypass the country specific country slots limits imposed by Megaupload while downloading files.
Install the extension. Enable the extension before starting a download from Megaupload and then disable it once the file download has started.

Direct Download like to the extension here