Well my first instinct is that you have quite a large file there..
804MB is very large, and the larger the file, the more prone you are of waiting hours and hours and then it stuffing up on 99%.
Firstly, let's assume the problem is solely because of the file size.
In WinRAR, find the file and right-click it, and click 'Add files to archive':
Next, name the file, change the type to 'RAR' and set 'Split to volume, bytes' to Zip100:
It should convert your very large file into about 8 or 9 small files you string together.
Upload all of these to Megaupload one-by-one (the smaller file sizes should allow it to take 1/8th of the time for each file, and also might have a better success rate.
The recipient at the other end just needs to download each file one-by-one, then put them all in one folder and WinRAR will piece the files back together and create your video again.
It's a little cumbersome but that is a very large file you've got there
Let me know how you go, and don't forget to log into your Premium account when you upload!
*LATE EDIT*: Just re-read you're using Wireless Internet.. uploading huge amounts over Wireless can be difficult anyway because of the "not so reliable" nature of Wireless. When something travels through ethernet all the way to the internet company, nothing can get in it's way. When something is travelling through the air, all sorts of other electro-magnetic interference (other signals, mobile phones, sometimes even cordless phones or microwaves - but they usually operate at a different spectrum) can get in the way of the signal, and ultimately, break it down. Just something to consider
Edited by Deon, 24 February 2010 - 06:39 PM.