Using regular expressions to parse out strings is not a good solution long-term, since the developer may change the code on the server and your code will break. Those tabs show different content depending on what data is posted. If you post the correct data to the script the information you need should be returned. Did the proxy show you the form POST data?
The "861.738/2013" is the Número do processo and it's a form field, so the year is the second part (after the /) and the 861738 is the first part, with the dot (.) removed, it seems. You'll have to add those values directly in to the URL, or provide form fields to allow the user to select or enter them.
