I had the same problem today. Granted, I said "maybe" because I have a wacky schedule - but I went to the calendar, clicked on the link, everything - nothing happened. I couldn't find a way in, and saw two people confirmed aside from the event coordinator. So I also watched a recorded orientation video (1). Also watched Rob Klapper's welcome message on Facebook in case the webinar was on Facebook (it said FB online?).
Oh well, I figured it was me not understanding something, or not being 22 and not hip enough to the digital generation :(