Accessing Webinar RSVPs

[Serpentor]

We have one user (K) with the "Webinar" license in our organization. They were recently on leave, during which time we moved the "Webinar" license to a different staffer (S), who set up a couple of recurring webinars. The usual webinar host returned, and we returned the license to them.  Because we hadn't set them up as a co-host while our interim host was holding the license, the usual host could not start the webinar. And because they no longer held the webinar license, the interim host could not start the webinar. This part all makes sense.  

The part that we're stuck on is this:

• Many had RSVPd for a Webinar on Monday that had been set up by the interim host -- we weren't able to start it because of the issue described above. We'd like to contact those people to apologize, but we don't can't access the RSVP list anywhere. 
• With the Webinar license restored to the interim host, we can see upcoming webinars, but we cannot see previous webinars -- the "Previous" tab says "You do not have any previous webinars."
• I've looked around in the "reports" section, and I don't see any reports that would give us RSVPs for past webinars. 

Is there any way for us to access the RSVP list for a past webinar that we weren't able to launch? 

[meriment]

We regularly backup our webinar registrations to avoid this situation. There are two ways to do this. You can either use APIs or we use Salepager which extracts the registrations automatically and generates a csv we can save.