Sorry I'm unable to make it work here but simply because their website doesn't work.
JD has handling for it.
Also the "password dialog" doesn't ask for a password in this case: It should ask for a Referer.
Either way you can override it by doing e.g. this:
player.vimeo.com/video/123456789?forced_referer=aHR0cHM6Ly93c3BvbGN6ZXNueS5wbC90ZWF0ci1vbmxpbmU
(Referer = base64 encoded - you can use HEX encoding as well)
If there is any way I could get that website working I could probably help you.
Do you have other example URLs of embedded vimeo content of this website?
As a last workaround, you could always use
this manual download method.
-psp-