As of late, Web Browsers such as Chrome, Firefox, and more are restricting autoplay of videos to improve the user experience. In some cases, this will result in the video features of Wonder not functioning, especially during Broadcast mode (IE unable to see the broadcaster).
To prevent this, make sure 'autoplay block' is disabled in your browser. Or simply "accept" the notification from Wonder about "disabling autoplay block".
To understand what exactly this means for you, please see Google's comments here.