Sorry for all comments but it seem you misunderstand stuff :D

"And it always is. So why create it again?
(Admit it - you frantically clicked around this image to get rid of the Tooltip.)"
Right, The thing is that Winxp is trying to help the first time user, He opens Windows Movie Maker and it wants him to save his work in My Movieclips now how easy aint that to remember? My documents > My movieclips compared to C:\Program\Windows Movie maker\Saved\Accountname\My movieclips?
Its all a matter of helping the first time user :)