I looked it up. His name is Steve Zuckerman. See:
   http://muppet.wikia.com/wiki/Steve_Zuckerman - he did the whole
   song himself on a 4 track recorder and sold it to children's
   television workshop. He was only 20 yrs old and his songs became
   embedded in the minds of millions of kids (who are now adults) -
   that's gotta be pretty cool for him