The selection of video sites that Mefeedia indexes is extremely impressive. Right now, they are claiming 15,000 video sources in their index. They put together the following sampling of offerings on their blog.
* Major Video Sharing sites (YouTube, DailyMotion, Metacafe, Blip, Veoh, and many more.
* Web Series Sites (AllorNots, Quarterlife, BoingBoing TV, 60 Frames series, Next New Networks series, etc.)
* Video Blogs (Steve Garfield, Ryan Is Hungry, etc.)
* TV Sites (Hulu, CBS, ABC, and others)
* News Sites (CNN, MSNBC, ABC News, CBS News, etc.)
* Music Sites (Imeem and others)
Obviously Mefeedia has the content and that is what really counts in a useful multimedia search engine. However, I tend to agree with Marshall when I say that the interface needs some work. The layout and colors just don't quite flow well for me yet. The search results page for established shows like Heroes, for example, have a much nicer look than a standard results page, like this one for Super Smash Bros. Brawl.
Despite the less than perfect interface, Mefeedia has very good community features. Playlists and subscriptions allow you to track your favorite users or content through RSS feeds, which is nice for those of us who live in Google Reader. I think that Mefeedia has something really solid here. Mefeedia is definitely worth checking out if you're looking for content beyond YouTube.