I was just randomly googling nsisbi just to see if there were any issues, and I found this thread. So I joined up just to let you know what the problem is.
Both official nsis and nsisbi currently have the same limit on a single file added to the installer, it's 32bit minus the top bit which makes the limit 2GB. Official nsis would never hit this limit because the datablock limit is also 2GB. Nsisbi has a 64bit datablock, which makes the 2GB single file problem clear.
So yeah, thanks to this thread I have added 64bit support for single files, but the problem is that other limits now play a role (codecs, file systems, etc). The lzma decoder had a 4GB issue, which I did a quick fix on.
The next version of nsisbi should be out with this feature a few weeks after the next official nsis release (3.06), which I believe is about 2 months away at this stage.