MovieSherlock is a YouTube downloader for the Mac platform. When you see a YouTube video you want to save locally, you invoke MovieSherlock and it handles the download for you. MovieSherlock can convert formats, as well as provide search integration. The Lite version of MovieSherlock sells for $14.99, while two more-powerful editions sell for $24.99 and $39.99. There is no free evaluation version.
The MovieSherlock interface lets you type in the name of a video you would like to watch, and it will search YouTube for the content, download it, and launch it in a player. Converting the format as it downloads is a part of the process MovieSherlock undergoes, and HD clips can be downloaded with the non-Lite versions of the software. When a clip is downloaded from YouTube it can be added to iTunes automatically. If you have multiple YouTube downloads going on at once, MovieSherlock can act as a download manager.
The problem we have with MovieSherlock is not technical; it works fine and we had no problem with it. But there are a lot of free or lower-cost apps that do the same thing. So, while MovieSherlock is a professional-looking and -acting piece of software, there's a lot of competition in the YouTube download niche, and most people won't be willing to spend $14.99 or more for these features.