That video is totally useless. Great, so you've got the lock bolt open, but you can't actually turn the lock far enough to unlock the door (if it is even reasonably fitted) because you have a big bit of stainless wiper blade in there, right in the way!
Also, I'm pretty sure that the trick he uses will only work on the few percentage of keys where the levers are all high lift. Any low lifts will block the wire getting through.
The Viscount can sometimes be a git to open, though, with those rusty steel levers. And if it works, it's not stupid - unless it only works on the bench!