asterisk users - May 2007 - Play a file on a channel from the Manager API

> Is there any way to play a file on a channel from the Manager API 
> (other than from Originate)?
This question was asked by someone else on the ast-dev list and the only
advice given was that Redirect was the solution.  I find myself with the
same problem now but I don't understand the response.

The situation: I need to play a file from the Asterisk Manager on a
channel that is currently in a call.  I don't want to break them out of
the call to play the message and I only want one specific channel to
hear the message.  In effect I want to ChanSpy the channel but to play a
message instead of speak to the person on the channel.

How does Redirect provide a solution?  

Thanks again,
George