YouTube Downloader is a popular, free program that enables you to download and convert online videos (legal content, to which you have the rights) for later viewing on your desktop or mobile device. It can convert files to MOV, MP4, 3GP, WMV, AVI, or MP3.
The name "YouTube Downloader" is terribly misleading because the program, in fact, downloads a whole lot more than just YouTube videos. On the developer's site, you can find an extensive list of additional supported sites including Facebook and Vimeo. This wide net of support easily pushes YouTube Downloader to the top of its category.
When you find a video you'd like to download, copy the URL of the video page and open YouTube Downloader. From there, you'll notice that the program automatically pastes the URL into the appropriate field. Choose your desired Download quality (Best Available is a nice option) and your destination folder, then hit Download. Once your download is finished, hit the Play tab to watch. The Convert tab lets you export to a different file format for playing elsewhere, and gives you a convenient mini editor for making minor alterations before your export. You can change video volume (or remove audio altogether) and splice footage by setting specific start and end times.