J-Downloader

It also let's you download Youtube videos in the form of mp3's and mpegs and other things like that! LE GASP! I love this program!

No shiet, anyone that's been on 4chon longer than 2 hours knows about this >

I just use a plug-in on Firefox that lets me download the videos in mp4 format.
Then i just go ahead and use Total Video Converter to convert it to whatever i want.

Sadly I had no idea this even existed. -goes into hole-

Yes J-downloader can do all these stuff it is quite amazing and I LOVE IT!!

Surprising. It's the lazy man's tool. Also does the majority of download site's captchas and stuff so all you do is copy the link and bam.