genre:animation
genre:comedy
genre:documentary
genre:educational
genre:gaming
genre:movie_feature
genre:music
genre:sports
genre:tv_show
Examples of searches:
ufo genre:documentary
charlie chaplin genre:movie_feature
data mining genre:educational
You can also use the genre: operator to better describe your search when you want to subscribe to a Google Video feed or to get an email alert when new videos are uploaded.
At some point in Google Video's history, you could browse videos by genre directly from the homepage, but you can still use the genre: operator without any other keyword to see popular videos from a certain category, like TV shows.