Yahoo has revamped its video service in a bid to keep up with competition from YouTube and MySpace. Since its launch 18 months ago, Reuters says Yahoo Video has mainly focused on professionally-produced and commercial videos. However, the updated service now puts more emphasis on user-created videos. Users can submit videos straight to Yahoo's service in a manner similar to YouTube, MySpace, and Google Video. It is also possible to tag videos based on their content, and to watch concatenated groups of videos about similar topics called "channels."