You have a few choices depending on who, or how many people you would like to keep off or on your video stream.

You can choose to broadcast only to Members.

You can choose to broadcast only to Friends.

You can choose to broadcast to Nobody (This will keep your cam running but only viewable to you)

For a more specific approach you can pick users in the room list, and prohibit them individually by clicking on their username options.

Guests in the chat can view up to 2 video streams simultaneously, while sharing video to unlimited multiple viewers.

* Watching yourself counts towards that limit.

Members can view up to 20 video streams at once, while sharing video to unlimited multiple viewers.

Expired Members enter the chat equal to Guests, and can view up to 2 video streams simultaneously.