Version 1.6 of the Vimeo app is now up on the boxee App Box.
This version has fixes for the 'Invalid Signature' error that popped up when clicking on Channels and Groups. Search didn't work either.
The reason for this was that Vimeo changed their authentication method for API calls. You can read more here: http://bit.ly/3wJn1f
I first included a secondary non-HD Flash playing option for lower end systems. Unfortunately this didn't work and I had to remove it. There are reports on the boxee forums of similar issues with the Vimeo moogaloop player. I'm working with boxee to sort that out, and it can hopefully be part of a future release.