Well, Vimeo doesn’t allow you to have access to this raw video(.MP4), but you can easily get it by just inspecting the page with the browser and removing the code snippet responsible for the video.
Like for example the video below that I removed from Vimeo’s official website, just inspecting the element and copying the code snippet.
<video controls autoplay preload="" src="https://01-lvl3-pdl.vimeocdn.com/01/4863/2/74317104/189249795.mp4?expires=1505088239&token=0ea4e3812d7a0bf4aa0bb"></video>
If you’re using Google Chrome, take the example of this print:
I hope I’ve helped.