I too had this problem. I downloaded the file onto my Knoppix Linux box with reiserfs file system using ftp (bittorrent is too slow for me) and then I wanted to transfer the file over to my windows box that has the DVD burner. When I transferred the file using apache webserver, the received file was always 47 Mb. I solved it by transferring the file using proftp and the full 4.1 Gb file then showed up and I was able to burn a DVD.

Hope that helps in some way.
KS