CNET reports that Yahoo is testing a video search engine. Not surprisingly, all the search bigs are getting into the game, with varying methods. Yahoo's own blog notes that indexing video is much harder to do than other web documents, as they're often hidden behind different types of code. As a result, Yahoo is relying in part on formal agreements with content providers. To help with the future addition of more video materials, Yahoo will support the Media RSS standard, which allows content providers to give them a heads-up when new video gets published.