"The mother of all demos" was used for this particular demo by Douglas Crockford in one of his public lectures about Javascript,
http://yuiblog.com/crockford/. I also recommend watching that, btw.
Besides the fact that this title is catchy - what's wrong with that? - it also tells more about the content than "the demo by Doug Engelbart from 1968". Surprisingly, not that many people know or care who Doug Engelbart is.