Every time I try and watch a video, a payment form comes up.
TROUBLESHOOTING: SUBSCRIPTION ISSUES
When you do not yet have a valid subscription and you try to watch a subscriber-only video, the site will display a form asking you to subscribe.
If you know you have a valid subscription, you may be signed-in with a the wrong account. From time to time, people forget what email address they used when they originally subscribed. So instead of signing in with their proper account, they accidentally create a new account using a different email address. It is therefore recommended that you sign out and try signing in under a different email address.
Alternatively, your subscription may have naturally expired. You can check the status of your subscription by going to your Profile page by selecting your Username at the top of the page. Then scroll down to see your status under "Membership Details".
If you do not have a subscription, then you can sign up for one. This will come with a free trial period during which you can experiment with the site. You can cancel anytime during your trial period and pay nothing. You will have full access to all videos during your trial period. Once you've completed the process, your trial period will start and you may begin watching videos immediately.