This is something that you need to be aware of when creating an Everwebinar. If the user is waiting for the webinar to start and then switched tabs in their browser the webinar won’t auto start when the counter reaches 0. However, if the use is waiting on the countdown page and doesn’t switch tabs it will auto redirect when the counter reaches 0.
Possible Solution
You should have a text message on the countdown page saying that if the counter hits zero and the webinar doesn’t auto play that you need to click the refresh button in your browser. Hitting the refresh will sole the issue.