That's what I used on my ultravids. They have a little post adapter that goes on the bridge of the binos. You'll need to pry the plastic cap off the bridge which is scary but is okay. Then attach the little post adapter and you're good to go.
The problem with the Uni-dapter specific to the Ultravids is that the Ultravids don't have a threaded bridge. Outdoorsman's has a specific post adapter that is held onto the binos via small allen screws, at the bridge hinge. The nice advantage of the Outdoorsmans as well is that once you install the bridge adapter you just leave it on and then getting into the tripod adapter piece is a quick-release fitting which works very well.
If I recall correctly it doesn't so much unscrew as you have to pry it off. Underneath are no real threads. Just a post that the adapter slips over and then is held together by 3 small allen screws (think a christmas tree stand). This may have changed from the Ultravid to the Ultravid HD? I just saw this on the link you posted under the adapter for the Ultravids:
"**NOTE: At the current time, Leica has changed the measurement of the part that this adapter fits on and right now we can't guarrantee this adapter will fit properly. We are waiting to get an accurate measurement of the new part before we sell anymore of these. Sorry for the inconvenience"
Yeah, that's exactly why I was wondering. I had that Jim White adapter ordered and it was cancelled, they changed sizes and he is waiting for new measurements before he starts selling them again. I'll probably give Outdoorsmans a call and see if theirs is still workikng or if they're having the same issues.
Got my Outdoorsman's adapter in the mail yesterday, very slick piece of gear. You're right Gman, that's an uncomfortable feeling for sure prying the cap off the end of the bridge. Haha. I played around with it a while this afternoon, seems like such a basic piece of gear to get fired up about but it is really slick and makes glassing with the binos way more stable than i was expecting it too.