Out of curiosity, why does netizen limit files to 4GB? Is there any way around this?

The 4GB limit is due to a number of reasons. We were using certain Mozilla interfaces and file formats that limited file sizes to 32 bits or (4294967296 bytes). I've fixed this limitation by moving to a fully 64 bit implementation for the next release (which I'm still working on).

So at the moment, there is no way around this. But you won't have to worry about it for much longer.

cant package the file more than 2 GB

Yes,that's a bug. It's been fixed for the next release.