Well U Tube is a massive conglomeration of everything from the important to the crazy. I think that it just about drives you crazy with the reandomness of what comes up via searching on U Tube itself. A better strategy I have found is to search on Google, using the advanced strategy. Or if you know a good site you go directly to that, for example, canterbury Public Library had a delightful video of their librarians modelling the old floral smocks. In my haste, I thought I'd find that easily again, but not so thwarted by u tube sapce junk. I might have another go when I am feeling less rushed.
However, I did find this delightfully hilarious piece by Kelston Boys High: A Day in the Life of a Library Bag Monitor: http://www.youtube.com/watch?v=CUJpLddzXBk
Despite its drawbacks, I think that U Tube could be an excellent promotional tool. Imagine author events on U Tube. Of course, this could only be done with the consent of the author.