Wow, there's a wide variety of videos on YouTube - everything from Her Majesty the Queen's Christmas message to K.D. Lang in concert! There also seems to be lot of very frivolous rubbish posted by sad wannabes all looking for their 15 minutes of fame!
However, I can see the benefits for public libraries. How about a guided tour pointing out where our collections are housed, or You Tube storytimes for those parents whose kids are sick and so cannot make it to Rhymetime?