LeechVideo Convertor is a really good app that lets you download videos from pages like Youtube or DailyMotion and converts them into a format compatible with mobile phones, iPods or PSPs.
The program will run in the background and it only works by detecting the presence of the downloaded multimedia file.
At that moment, you'll see the application's icon on the website you are viewing.
Then, if you click on it, you can access the program window and then select the video format you want for the video you are about to download.
Remember, this application works under Internet Explorer, it does not support other web browsers.