I think I know how to solve the problem. Here is the discription of GetRight download manager version 5.2 beta 1 and beta 2:
The first improvment says that:
Fixes & Improvements in Beta 1:
Increase from 32 bit numbers (which maxes out at about 2GB for a single file) to 64 bits (which is about 8 billion Gigabytes). Should be good for another 1000 years or so!
TIP: How your disk is formatted can limit file sizes too. FAT limit is 2GB, FAT32 limit is 4GB, NTFS is unlimited. Info from Microsoft.
So I tried it and... it works! I've seen clear that the program have been downloading the file with the size of 4157 MB (Fedora Core 2 DVD ISO).