Here are a few of the video's that I found during my serach:
This is a book trailer for Scott Westerfeld's book Leviathan. This is a great way to get kids excited about books, especially those who are not readers. This is an example of a very professional book trailer done by the publishing company. This is one of the ideas that I talked about in a past blog post. Having kids create their own book trailers.
Here is another type of video that can be great. It's not necessarily the best example of book reviews, but I happen to link this vlog. I haven't seen it a lot, but one of the authors I follow on Twitter (Maureen Johnson) was a guest vlogger on here and I really enjoyed watching her and the guys who do this vlog. Again, students could do something similar to this creating book reviews for books they have read and want others to read.
There are many, many how to videos out there. I particularly like Howcast videos. There are a number of inappropriate ones that are actually humors, but I chose one to share about travel, since our upcoming 20+ hour flight home is right around the corner.
Finally, I'll share my two fun videos. One is again library related and what I originally was going to share. The other is one example of a video that my husband made me watch, which got us side tracked for 45 minutes watching more. Enjoy and don't get too lost in YouTube land.