I've created a Video content type, and added a Vimeo field to it. I've tried both with and without underscores in the name. The browser is able to load up a list of videos in a group, but not insert them into the CCK field. Clicking an item causes the browser to say "Gathering Image Data for Insert", briefly (< 1sec) say "Loading", then return to the group list.

The insert button has the path:

http://redacted.dev/vimeo/browser/fullvideo/0/fullvideo/0/YTozOntzOjU6In...