This is a limitation of the FAT32 file system, that you USB disk will be formatted with.
There is no easy way of doing this unless you are a bit of a techy, and don't mind tinkering a little.
Basically, (and I'm assuming you have Windows or a Mac at home?), you could install
Virtual Box and install a Linux operating system (
Ubuntu Desktop would be a good candidate). With this you can then format your USB disk to the ext3 file system. Once you've done this, you can transfer your recordings (regardless of size) to your USB disk.
Unfortunately, you can't read the ext3 file system on a Windows computer, but you could transfer the file to your Linux virtual PC, and then FTP or SCP to your Windows operating system.
An alternative would be to install the
modified firmware for the HDR, which installs an FTP server on the box, then you can FTP your recordings from the HDR over a network connection to your PC or Mac.