OK, I'm just telling you, that's not how you do it. To show the welcome screen, you must first erase your hard drive and reinstall OS X. Here I will tell you how to do that. First, you will need a bootable USB Snow Leopard install drive. To do this, you need a 8 GB or bigger USB drive. To get started, make sure the 8 GB USB drive in inserted in the Mac. Then open Disk Utility. Click your USB drive on the left. Then click the "Partition" tab at the top. In the drop-down menu, make sure you have "1 Partition" selected. Then name the drive something like "Install Snow Leopard" or "Install OS X" or really anything you want. Then make the format "Mac OS Extended (Journaled)". Now remember that what I will tell you to do next will erase all the data on your USB drive. So if you have anything important on it, take it off. Now click "Revert". Now for this part you need your Mac OS X Install DVD. Make sure the DVD is for Snow Leopard, or else your USB drive will not install Snow Leopard. Insert the DVD into your Mac. If you have already closed Disk Utility, open it again. Now click your USB drive on the left. Then click the "Restore" tab. For the source, drag the DVD from the left of the screen or from your desktop into the blank text field. For the destination, if not already there, drag your USB drive there from the left. Now click "Restore". Now eject the DVD. Once that's done, you have your bootable USB drive. Now I will tell you how to use it to erase all your data from your mac. Turn off your Mac and hold down the option key. Then, while still holding down the option key, turn on your Mac. Now select "OS X Install DVD" or something that sounds like it would install OS X. I don't really know what the name would be, because Disk Utility changed it. So just select the one that you think installs OS X and click the arrow under it once it is selected. Once your Mac boots, you will see the Snow Leopard install screen. DON'T CLICK ANYTHING YET!!! First click "Utilities" in the menu bar and select Disk Utility. Now select your Mac hard drive from the left. Then click on the "Erase" tab. Now make sure the format is "Mac OS X Extended (Journaled)". Then name the drive something like "Macintosh HD" or "Mac HD" or "Snow Leopard HD" or something like that. I recommend the default name, Macintosh HD. WARNING: WHAT I WILL TELL YOU TO DO NEXT WILL ERASE EVERYTHING ON YOUR COMPUTER, INCLUDING FILES, USERS, AND APPS. Now click the "Erase" button. The erasing may take a while. Once it's done, quit Disk Utility. Then press the "Continue" button. Then select your Mac's hard drive.Then press "Install". It may take a while to install Snow Leopard. Once Snow Leopard is done installing, you may see the welcome video. At any time you can shut down your Mac. Just don't go through the setup process. Shut down as quickly as you can after you see the beginning of the welcome video. Now your Mac is like new and the welcome video will show up at the next boot. Hope this helps!