From RsMa Software:
If you like YouTube, you need "Tube Downloader". Tube Downloader promises to let users save their favorite films to their hard drive and view them whenever they want. Tube Downloader can queue an unlimited number of videos for retrieval and download multiple videos at once allowing you to create large archives of your favorite content very quickly. The program is easy to use, just drag and drop or copy and paste the URLs for the videos you want to download, then click "Start" button. It also allows you to convert downloaded videos to mp4,avi, wmv, mpg, so you can store and play them on your iPod, iPhone or any other mobile device.