In order to handle a large number of presenters, the greenroom adjusts the quality of individual video feeds depending on whether or not they are in a live shot. 

Because of this functionality, it takes several moments for a feed's video quality to adjust when moving them into a live shot. In order to optimize this process, building a shot before taking it live will optimize quality between transitions. 

As soon as you click a particular feed, and you see the "start shot" button turn red the greenroom will begin receiving the full resolution possible from the feed.

Waiting a few moments in this state before taking your shot live allows for the highest quality output.