I gave a demo of Brie at the OOPSLA Croquet workshop in October, and Julian gave one a couple weeks ago at C5. Alas, no video, but the Brie papers are here and here.
This terrific video of the Alternate Reality Kit was made at Xerox PARC in 1987. So, of course, it’s not actually Brie, but it does give a lot of the feel of what we’re going for. There are a few UI differences and the ARK is only 2D, but the main thing is that Brie is synchronously collaborative, and therefore eminently shareable.
Another related thing (without a cool video) was PARC’s Thing Lab.