EDIT: Pornhub changed video protection methods. The pornhub streaming script no longer works. You can still grab 720p sources from "youporn".
If you want to use the older version that logs into premium accounts you can find it at https://github.com/Zebraslive/Pornhub-Premium-Video-Streaming/blob/3be7ed25ca169b666305405693bcfc17ef57bdeb/api.php