Replay Media Catcher can download youtube videos for free, rename them automatically, extract mp3 files for free and even convert recorded flv videos!!! Even though it is FREE, you get high quality technical support from Applian technologies. I don't see any better alternatives to that on the market!

And you can even learn how to use Replay Media Catcher using one of the many free video tutorials

Video Tutorial: How to record YouTube Videos for FREE with Replay Media Catcher