Does SESI have a Beta program, if so, how does one go about getting onto the Houdini Beta program?

Is it an “invite” only type of thing?

Yup, we have a beta for every release. It's only open to commercial customer's on our Annual Upgrade Plan and of those, we invite users who have given us good and regular feedback in the past. Customers on AUP can contact their SideFX Sales Representatives for access.