I installed the Direct-YouTube-Downloader on a friends XP Home computer and it had its search and home pages hijacked by the Babylon Toolbar. I uninstalled it but that didn't remove it from IE8 or Firefox13. I had to manually remove it from IE and needed to do a direct edit of the user settings files for Ff. I would NOT recommend software that includes such nasty software. Oh and I did install it on my Win& system without incident though I wasn't using the same security software and had better control of the install.
I do recommend YTD YouTubeDownloader - free. It akes no attempt at installing toolbars and it will also do playlists, file conversion, and download in selected format or highest possible. My one caveat with it is DO NOT go to the supported sites link since it has several likely porn sites in the list.