I was the one that suggested YASU, which I use on all my Macs with no problems.
I don't think you can change the settings and accidentally force YASU to delete pictures and movies from your computer. It's a fairly safe utility that I have used for years.
YASU doesn't do anything outside of the various caches folders, so it's unlikely to delete your own files - unless you had your files in simply the wrong place...
Your pictures and movies (I'm assuming you use Apple's software, like iPhoto, and iTunes, etc) will be in the your user (home) folder, in either the Pictures, or the Movies folder.
Are you saying that those folders are now empty?
If those folders have files in them, what leads you to believe that your pictures are all gone?
If the pictures (the files) are actually gone, you can get them from your backup.
If I recall, you began here wanting to clean your hard drive, because it was getting full, correct?
A full hard drive, particularly if you began to get messages telling you that the hard drive is full - and you continue using the drive in spite of the warning messages, can occasionally cause corruption of files, and problems with the drive directory.
I suggest as a next step, the you boot to your OS X installer disk, and run Disk Utility from the menus - so you can attempt to repair the hard drive directory.
If you have a bootable backup, you could also try booting from that to repair your internal hard drive (again, using your Disk Utility)
Let me know if you have neither a bootable backup, or an OS X installer disk. This is one of those times where the installer DVD is more valuable.

There are still other repair options, so let me know if you need to pursue other choices.