Seems like some people still have problems with downloading videos and MP3's from youtube.
Here's the 3 best, FLVDirect is the best of these.
1. FLVDirect
FLV Direct
Downloads videos AND mp3's really fast with many options.
2. Video2Mp3
YouTube to MP3 Converter - Video2mp3
Downloads MP3's, but kinda slow.
3. Youtube Downloader
YouTube Downloader - Software to download and convert YouTube video
Kinda messy tbh. I wouldn't use.
Summary: If you need a video or an MP3, FLVDirect is tha shit!