If you're looking for one particular, recognisable YouTube video amidst a galaxy of copycats and look-alikes, Wibe7.tv offers a vast wall of thumbnails that pop up the clip, no visit to YouTube required. It's very similar to (and inspired by) the previously mentioned, just-the-pics-ma'am Flickr searcher Compfight. Once you've searched, the results can be sorted by relevance, views, user ratings, or date published. It looks like you only get one page of results, so if the clip is buried deep inside YouTube, only search term refinement will dig it up here. All told, it looks like a powerful and quick way to gun through YouTube videos to find what you're looking for.