"Subscribe Now" button in the video interrupt screen

I’m using the video theme to create a website of piano tutorials. I would like to set some videos as free to all registered users, and have used the video options to limit the videos to 45 seconds.

In the interrupt screen that appears after the 45 seconds are up, there is a “subscribe now” button. How do I configure that subscribe now button to jump to the registration page? There is a “login / register” option in the menu that is functional, but it is really small and hard to see, especially when the interrupt screen has a “subscribe now” button that looks like a different option than “register”.