Here is a guide to install the Mac OSX Snow Leopard theme on Ubuntu. First you need to download the theme pack from gnome-look. When downloaded extract the content of the Mac_OSX_Themes.zip to your Download folder. Open the Max OSX Themes folder followed by the Snow Leopard folder.
Inside the Snow Leopard folder you will see the following folders:
Arbeit Macbuntu 1.1 (GTK+ theme)
arbeit-macbuntu-icons-new (icon set)
Shere_Khan_X (pointer)
Snow_Leopard_wallpapers (wallpaper collection)
T-ish_Brushed-Overlaid (GTK+ theme)
Compress all folders (except he Snow_Leopard_walpapers folder) to a tar.gz file. You can do this by clicking with your right mouse button on a folder and select Compress. When all the folders are compressed open your Appearance Preferences manager and select the Theme tab. Now drag and drop all the compressed files into your Appearance Preferences manager and that’s it!!
Download Snow Leopard theme pack
How do you get the moving background??
Do you use a video then set it as it is?
I used a-desk for the moving background. You can get it from: http://gnome-look.org/content/show.php/Animated+Desktop+(GUI)?content=88248