Like its name suggests, YouTube Downloader
allows you to download YouTube videos onto your device. To do so, you only need to copy/paste the video's URL into the interface, then select the output format and destination folder. It supports AVI, MPG, MOV, WMV, iPod Video, iPhone Video, PSP Video, MP3 file formats.
The software also acts as a converter and lets you change the format of a video into one of your choice.