This article that was in Daring Fireball here makes an important point. I'll quote the some of the same text as Gruber:
"Unfortunately for the average person, the file system is so complex that everything outside of the desktop and the documents folder appears to be a vast labyrinth which most likely hides booby traps and minotaurs."
I find this true almost whenever I try to help someone find a video file to upload. I don't know the solution to this except maybe for there to be default locations for various kinds of files. Windows and the Mac try to do this in limited ways but it fails when you are trying to do something that varies in any way from the usual use case that the user knows.