Attendees Register Through GoToWebinarIf your webinar attendees register through GoToWebinar, you can identify prospects who converted by the campaign that is assigned to the webinar connector. All prospects that are created via the connector will be assigned this campaign. Use Pardot's campaign reporting to see which prospects converted on your webinar campaign. See How are prospects associated with campaigns? to learn more about how Pardot campaigns work.
Prospects Register via Pardot Forms with Completion ActionIf want to report on attendees that convert on individual webinars, you'll need to use Pardot forms and completion actions to register attendees. Using a Pardot form for webinar registration will let you know exactly which webinar a prospect converted on.
See Registering a Prospect via a Pardot Form for instructions on creating a registration form. To report on prospects converted on a form, simply view the form's report and click the Conversions link. You can export the prospects as a .csv file, or use prospect table actions to add tags, add them to a list, and so on.