Youtube-mp3.org is the 900 pound gorilla of Youtube to MP3 converters, at least as far as traffic is concerned.
The downside of this popularity is that Youtube-mp3.org has attracted the wrath of Google, which have banned the site from accessing Youtube’s servers.
In other words, the first search result in a Google search for “Youtube to MP3” is broken — and Google broke it. Go figure.
I think, as an operator of such a site, you should be prepared to having to work around all kinds of technical challenges.
Youtube to MP3 
But there’s nothing wrong with it? No cookies or viruses or anything?
Not that I found, no.