From GreenTree Applications:
YTD Video Downloader for Mac is more than a Youtube downloader for Mac. It allows you to download HD and HQ videos, from dozens of sites and convert them to other video formats. The program is easy to use. Just specify the URL, similar to a Youtube downloader, for the video you want to download and click the Download button. From there, YTD Video Downloader for Mac will download the video from the URL you specified. The program also allows you to convert downloaded videos for iPad, iPod, iPhone, PSP, Cell Phone, Windows Media, and XVid, or play video that you have previously downloaded or converted.
The YTD Video Downloader for Mac interface includes a tabbed format for easy downloading, converting, and playing, and a new Activity tab allows you to keep track of multiple downloads and conversions in real time. The program has the ability to download full playlists as opposed to just one video.