Barry, I'm sure you're wrong about the copyright laws in the US. Disney even once tried to stop the Boy Scouts and Girl Scouts from using their songs at campfires without paying royalties. They backed off in the face of well-deserved public pressure and ridicule, but legally, I'm pretty sure they were on solid ground.

I do know that when "cover bands" perform at clubs, either they or the club pays royalty fees for the use of those copyright protected songs.    And when bigger name artists do concerts and perform songs they didn't write, you betcha they have to pay royalties for such commercial use.

YouTube is a little fuzzier, since there's no money involved directly (though many people do use the site as promo for their own music careers).   But the copyright holders can -- and sometimes do -- make people take videos off of YouTube because of copyright violation.
No, in the US you don't legally have the right to perform someone else's song in public -- much less record it and post it on line -- without the permission of the copyright holder.

(I'm sure we have about a dozen threads here at Mudcat on this topic.)