On Megaupload free account you can download around 1gb (or something close) and then you must wait for another 1gb and so on. But there are some hacks to bypass the limits, like:
- disconnect/reconect if you have dynamic IP (esp. wireless net)
- search for firefox extensions http://www.google.com/m?q=MEGAUPLOAD+FIREFOX or another methods http://www.google.com/m?q=MEGAUPLOAD+DOWNLOAD+EXCEEDED or something like that. This extension worked a year ago but only with firefox 2 (see http://oldversion.com )
Mediafire doesn't have these limits but probably it's a bit slower than MU.

