He mentioned brute force programs. Such things will check every possible combination of letters up to a certain length trying to crack a code/password. If the password could be up to 30 characters, the brute force program would need to check all combinations up to 30 characters in length. Or, if it could only be 8 characters, then you'd only need to check up to that length. In any case, duplicates wouldn't happen using the code provided regardless if you were looking at 100 character strings or 2 character strings.
