You could move it back, and it might still work.
You can't simply move programs from one drive to another, as you do your documents, because of the way applications are installed. When you installed the software, it located drivers and links in windows system files, etc. etc., that it uses when it functions as an application. When you move the program files, you break these links, and it can't find the other parts of itself anymore.
The best thing to do is reinstall the software to the new location, which is simple if you still have the cd.
If not, you can look in your program files folder under WinDVD and see if you can locate the setup.exe file, and attempt to run it from the new drive. This may be able to install the application anew, and during setup you can point it to the location where you want it to reside.
Failing that, you might try going to add/remove programs in control panel and see if there's an option under the WinDVD to change, rather than simply remove the program. If so, you could conceivably run the setup from here, by opting to change. (I suspect this won't work, though, for the same reason the program itself doesn't work.)
Otherwise, you can download a copy of this software from the web. Here's one link:
http://www.tucows.com/preview/228053
Unfortunately, that doesn't help you recover your license key, which is required to keep that trial version functioning. For that, your best bet would be to contact Intervideo support and plead your case...http://www.corel.com/servlet/Satellite/us/en/Content/1152796555474
(Note the company has changed hands since then.)
Perhaps someone sneakier than I knows how to retrieve that lost license key from your program files. Just in case, don't delete them or uninstall the program until you've decided to abandon it.
But if they want you to pay for the old one, consider upgrading to a newer version that's compatible with your operating system. It will take a little relearning, but DVD software has definitely improved since 2002, when that was first released.
You have my sympathy, and best wishes for a successful outcome!