@rightnow
The "primary" performer of a scene is taken from the Next area of the Now Playing side bar so you can populate that area and then start a scene that can make use of whatever you have queued up there. If you have a dual screen system you can ***** to the active card area directly while the scene is active.
Only the primary performer can be controlled in this way, there is no control over the other performers other than to disable cards and clips you do not want to be used.
The primary performer is just the first clip mentioned in the scene's .scn file. In many scenes this is the main/most prominant/central performer, and scenes should preferably be written with this in mind, but it is not always true so the "primary" performer may actually play a ***** background role.