We just released Zapier integration. it is still in beta stage right now (which means only available by invitation but it is fully functional, please watch the video to see how you can get the invitation on your own). You can either use it as trigger for when someone registers for the webinar (more options coming soon, e.g. when someone attends, sees offers, or for reminders etc), or as action i.e. register someone for the webinar automatically when a particular event happens.
How to use Zapier as Trigger
How to use Zapier as Action