From their T&C page -
All account balances are held in VirtaPay virtual currency. VirtaPay maintains a virtual currency that is autonomous and independent of all nations and governments. The VirtaPay currency is denominated in dollars and cents (similar to the currency of the United States and over 20 other countries). The VirtaPay currency is currently in a closed system, and cannot be exchanged or spent outside of this system. Our plans include person-to-person transactions, integration with merchants and shopping cart systems, and much more. As is the case with any currency, once the VirtaPay currency comes into widespread use, its value as weighted against other world currencies can and will fluctuate due to market forces such as supply and demand, etc.
Always read the small print people.