No there are no constraints on the task. The flow to change the status to attended if they are in the list of attendees, is Add to SFDC Campaign, Campaign is WEbinar 041813, Status: Attended
As for attendee status, I am not sure what you are asking. This event was created in WebEx in the meeting center as opposed to the Event center. From what I understand marketo doesnt communicate with the meeting center and that is why we run the smart campaigns for these kinds of events.
Does that make sense?