Put the ORIGINAL dvd in your computer
Browse to your DVD in the "Please select the root folder" window
Click on "Create sums"
Click on "Select All", then on "Add Recursively", then on "OK"
When prompted, save the checksum (Save as) on your harddrive, let's say on C:\ (Select it in "Save in"), and name it dvd (File name: "dvd"), click on "Save".
Put the COPY in your computer
Start a command prompt (Start>Run>Type CMD and click OK.
Type "CD C:\"
Type "fsum [YOUR DVD-ROM LETTER (D, maybe? -- look in windows explorer if you don't know)]:\ dvd.md5 /R /V" and press ENTER
Let the program do the verification
Make sure that the output looks exactly like this (Without a Changed files or a File access errors error):
Files not changed.
Processed xxx files in xx folders with total size xxx Mb.
Elapsed time: xx:xx:xx Average speed: xxx Mb\Sec.