PodZinger is a search engine that allows you to search within audio and video content on the web. As is farily obvious from its name, the technology can be used to search for keywords inside of podcasts, which is pretty cool, but now PodZinger has a specific YouTube search function that allows you to do keyword searches on audible content inside YouTube videos. I'm sure that you see the irony like I do: Google, a search company, owns YouTube, but does not have the same search functionality for its YouTube content that PodZinger provides. What is more ironic is that PodZinger uses Google AdWords to monetize its search product -- search results pages on PodZinger feature Google advertising.
Link -- PodZinger
Link -- PodZinger YouTube search