ROBERTCOOGAN  I don't want any YouTube downloader app to auto-convert the videos I download and auto-import them into iTunes. Annoying!

This is why I really like YouTube Downloader - it's super-simple to use and lets me pick the destination folder for the videos.

One small problem has appeared under Snow Leopard however, my cursor will dissapear and I have to shake the mouse around in order to get it to reappear, or command+tab to switch to another app to get it to reappear. Hopefully the dev will issue an update that will get rid of this one small bug.  
(Version 1.8)

JEFF H.  Hit download link and got some duplicate file searching software instead...WTF?  
(Version 1.8)

MACDMITRY  Tryed this software a half year ago - didn't converted downloads. As I wasn't able to view flv files - useless for me  
(Version 1.8)

VERYCARLA  Does the job nicely. It's a Java applet, which shouldn't put anyone off - it's cleanly designed and very straightforward. Just double-click the .jar file and feed it the URLs of the YouTube videos you want to save, and off it goes.

One very nice feature is that it will extract the name of the video from YouTube, so you won't be left with a directory full of "download 1.flv" files wondering which was which.

However, it doesn't do any automatic conversion, so if that's important to you look at another app.  
(Version 1.7)