MediaElement.CurrentStateChanged Event

It is possible for the CurrentStateChanged event to be raised multiple times before its event handlers are executed.

Although this event occurs when the CurrentState becomes invalid, that does not necessarily mean that the CurrentState property has a new value. For example, the CurrentState property might have switched from Playing to Buffering and back to Playing so rapidly that only a single CurrentStateChanged event was raised, in which case the property will not appear to have changed values. Also, your application should not assume an order in which the events occur, particularly for the transient states such as "Buffering". One of the transient states may have been skipped over in event reporting because it happened so rapidly.

Silverlight

Silverlight for Windows Phone

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.

Reference