I found this pretty interesting blog-post by Youtubes' Shiva Rajaraman about the distribution of ratings in Youtube videos. Seems almost no people rate videos with anything else than five stars. As soon as I read it I did a similar plot of the Filmtipset dataset I've been working on lately.
It seems that there's quite a difference in the way we rate videos and movies. Below is a plot of the rating distribution in Filmtipset and a copy of the one from Youtube. The of the x-axis on both images is 1 to 5.