Can your App sync ALL of our old Webinars?

Yes, it can. You actually have the ability to define how far back we're syncing your Webinars. Whether you have one GoToWebinar account or multiple, you have the ability to define (By Webinar Account), what date range of old webinars you wish to sync with Salesforce. 

To define a time range, go to the “GoToWebinar Users” tab, open a record, click on “Edit” then insert the date range in the “From” and “To” fields in the right column. After clicking on “Save”, click on “Get Webinars”.

NOTE: If you have hundreds and hundreds of old Webinars to sync (or thousands of “Registrants and Attendees”, to avoid Salesforce limitation errors, you’ll need to click on “Get Webinars” multiple times, each time resetting the "data range ot a different period, and keeping the date range to one or two months until you’ve completed synchronizing all of your old webinars to Salesforce.