Well, if you own a original copy of the game I suppose you use the documentation that follows to bypass the copy protection. If not I suggest you buy the game.
Since I am the one who reversed Nippon Safes for ScummVM, I can tell you that ScummVM behaves exactly as the original version in this regard. Whoever posted that video on youtube therefore used a modified (cracked?) version of the game.
If you have the original booklet and can read, selecting a character should not be that difficult. As Jonatan said, this is a protection feature that cannot be bypassed.
Well, even if you own the manual the quiz for the character selection is not all that obvious...
I had to try many times to get all three, of course once you know them you can just write the codes down.
For those who are stumped the following advice should be ok to give since it still requires the manual to look up the actual codes, it's just to help with the selection of a specific character: