I was getting the insufficent error too.
All that i had to do to resolve it was change the virtual hard disk size to 16GB and the installation started
BTW I am installing Windows 10 64 bit on a Sandisk Extreme 64GB Usb3.0 using an MSI GS70 Stealth running Windows 8.1 64bit.
Will let you know how it goes.
All that i had to do to resolve it was change the virtual hard disk size to 16GB and the installation started

BTW I am installing Windows 10 64 bit on a Sandisk Extreme 64GB Usb3.0 using an MSI GS70 Stealth running Windows 8.1 64bit.
Will let you know how it goes.