No, you can use your credit card for flights with any airline or travel booking service that accepts credit card payments.
You'll still earn Velocity Points per $1 on eligible spending. But you'd miss out on any additional points and status you'd get if you travelled with Virgin Australia.
If you want to use your Velocity Points to make the booking, you can travel with Virgin or any of their partner airlines, including: Air Canada, Delta, Singapore Airlines and Etihad.