Google Video has a new section on the homepage: Blog Buzz, that features the videos from YouTube and Google Video that are discussed the most in the blogosphere. I assume that the ranking includes Google Video, even though the current top 10 videos are all from YouTube.
For each video, there's a link to Google Blog Search, where you can find the blogs that discuss those videos. It's a interesting to note that a search for [ link:http://www.youtube.com/v/8K_NQe57C-k ] in Google Blog Search returns not only the posts that link to the video, but also the posts that embed it.
There are many sites that try to find the hottest videos, by monitoring who links to them. Technorati sorts YouTube videos by the number of new links in the last 48 hours. Tailrank also focuses on YouTube, but gives priority to important blogs. Megite looks at videos from more than 20 online videos sites and takes into account the importance of a blog when ranking videos. There's also BlogPulse that also monitors Flash animations and shows a daily top of the most linked-to videos.