How do you know it's "someone else"? It's the login page, you don't know who you're displaying the page to yet.
And if you mean a different salt every time the page gets loaded: doesn't that completely skip the supposed point, which is to give the user a recognizable visual cue that they typed the right password?
The demo seems to highlight its use as a visual cue that your confirmed password is the same as the original. Not that useful in my opinion, as one attempt at creating an account with non-matching passwords will tell you they don't match anyway, and you (usually) only create an account once.
Still, pretty cool demo and very nice colour schemes.
And if you mean a different salt every time the page gets loaded: doesn't that completely skip the supposed point, which is to give the user a recognizable visual cue that they typed the right password?