A few things.
1) Just because you define a function called load() doesn't mean it will be called on load.
2) If it was called on load the page would be stuck in an infinite loop as the page would submit, re-load, and re-submit indefinitely
3) I don't think you need a form submit or hidden form element at all. Just use the "before page load" trigger in the update record server behavior and set the value to: paid directly from the Server Behavior.