Hi,
I think something is missing in this wonderful script that is Virtualbox-Portable. When modifying configuration file to update all the virtual hard drives path you are only considering *.vdi files and not *.vmdk. I know this is not the standard virtual disk file for Virtualbox but it makes use of it.
In my case, I have installed Virtualbox Portable on a FAT partition of my USB drive. I have also a linux partition on this drive which contains my installed Ubuntu. I created a vmdk file with vboxmanage.exe to access directly the USB drive.
It would be great to manage *.vmdk as equivalent of *.vdi.
Thanks for your work
Regards
Stephane