Zamzar

http://zamzar.com/ is a web application to convert files.  It allows user to convert files without downloading a software tool.  Users can type in a URL or upload one or more files forom their computer, Zamzar then converts the file(s) to another format.  Zamzar supports the downloads and conversion of videos from a range of sharing websites.  The following websites that Zamzar can convert their video formats to the format you need:  Youtube, Google Video, Revver, PutFile, and etc.  I enjoyed using zamzar.  I never used Zamzar but I will be using it in the future.