Re: Try searching for a video on vimeo through Google. Guess what, it works
Missing the point a bit. Try searching for a video that's on vimeo through Google and see if it suggests it. They may show you vimeo results if you specifically ask for them, but for vimeo to become an alternative to youtube the search ranking needs to show no respect to the site hosting the video. Do Google favour youtube or does youtube's popularity put it at the top of the search results?
This is the classic point, continually downvoted here but not rebuffed, that Google search can't be trusted to be fair when they have a product to promote.