I don't see how the two are related. Hulu is for consumption of produced video where as Vimeo is for oriented towards user generated video. They don't fulfill the same need.
Yes I realise this. User generated video may not be Yahoo's priority right now but on the subject of video, studio produced content is more than likely to be. Everyone's throwing their hat in the ring when it comes to streaming tv online. You can be Yahoo wants in on some of the action. What's going to be a better revenue generator?