Apparently the deaf (is that PC?) are using YouTube as a public forum, in much the same way most of us use threaded and flat forums like vBulletin and phpBB. What a brilliant use of technology, and a perfect example of one of those things that seems utterly obvious when you think about it. But you didn’t think of it. :)
The reason I didn’t think of it is because deaf people can read text just as well as non-deaf people, so I would never have seen a need for a non-textual forum for deaf people.
Probably my use of the word ‘public’ was a bit off there, since it’s the privacy that’s the cool thing. But then it’s not really private, it’s just the equivalent of speaking Irish on the Tube. I’m confused now. :)