There are only two Anthem controls on this page: the Anthem.Panel (blue border) that surrounds all the other controls, and an Anthem.Button in the bottom right corner to demonstrate that you can embed Anthem control inside of an Anthem.Panel. When AddCallBacks is true, the Anthem.Panel will convert all of the child controls to use callbacks instead of postbacks. The Anthem.Panel also has Pre- and PostCallBackFunctions defined to display a message while the callback is being processed on the server. Note that these are inherited by all child controls. Callbacks are generally very fast. You may need to turn on the server delay in order to see the message.
If you want a particular control in the UpdatePanel to use a normal post back (e.g. to start a file download), then use the equivalent Anthem control and set the EnableCallBack property to false. For example, this Anthem.Button will initially perform a postback. Each time you click on the button it switches EnableCallBack.