When you are in a chat room where people are sharing their web cam video you will see a panel of video view windows to the left of the group participant list. You can tell who is publishing their video by the camera icon beneath their name to the right. If you are currently viewing someone you would see a green 'eye' icon instead.
When you place your cursor between the chat box and webcams you'll see a drag bar appear. This is how you will adjust the size of the chat box, active webcams, and so forth.
Just hover, click, and drag your cursor. It's that simple!
Right above the chatbox are where you will notice users that are 'now live'. Just click 'View Webcam' to open their camera up.
Top right is where you will notice the members who are 'Talking Now', how many are 'Waiting', and you can search for members in the room.