Ubuntu :: Notification Dialog To Display Script For A Screen Cast?

Is there a program there that can display screen cast commentary as text in a transparent window centered on screen ( in a window that looks like a GNOME-Do window or Growl notification window).

Feature am looking for is almost like the alossage mode in emacs. But instead of showing what is being typed, each press of a shortcut key displays in a notification dialog in the lower 3rd of the screen one line at a time from a predefined text file.

So now - I can define a text description for each step in the screen cast in say ~/castScript.txt During screen-capture press the shortcut key to display each line of the text from the file onscreen