Try using Xilisoft Video Converter. http://www.xilisoft.com/ Just locate your file, change so it converts to .wmv. Then fix the settings to the right. I'd do Bit Rate 3000, and then just keep the size at 800x600. Then press Encode, and it should say that you're using a trial. Just press Ok, and it will encode.
Actually, there is like a 2 GB limit, just go to the multi upload, and install the plug in thing, then you can upload more than the normal size.