given that any exe can be run as a screensaver, this should be fairly easy thing to add.
Yeah it's just a case of how you trigger the bit we want to see. Using the normal exe for the screensaver would mean that when run, the main menu sould be displayed. I could trigger the playback code after a certain period of no user input but that would still mean having the menu displayed for 20 or 30 seconds.
The alternative would be to make the playback code part of the game intro. That way it would run as soon as the screensaver was triggered and the user could scip it to start the game properly. A bit of testing needed me thinks.