Some web browsers, including Chrome, restrict autoplay of videos to improve the user experience. In some cases, this may 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 Wonder notification to "disable autoplay block".
To understand what exactly this means for you, have a look at Google's comments about it.