In a usual situation, you are able to watch a Vidyard video in fullscreen by clicking on the fullscreen icon in the bottom right of the player.
The icon is missing in Internet Explorer (IE) 9 or IE 10.
This is caused by the lack of fullscreen compatibility via API with these two browsers.
The solution is to use a query string in either the URL of the sharing page, or on the embed code to force our Flash player, rather than the default HTML5 version.
The query string is: