I don't know this guy, nor did I go to the link. One of the most underused or missed parts of people's musical education is this part. You should be able to sing a melody and then play it, basically first time thru. I am sure most players who have any ability can hunt and peck a melody on their instrument, just as they do on a computer keyboard, if they can't type properly. But if you really understand your instrument, music and have talent, then you should be able to do this. Many people think George Benson is singing along to his playing, but it is actually the reverse, he is playing what he is singing. It seems like a minor distinction, but it is not.

I know nobody here was discounting ear training. But many people just don't practice it. You don't really need a course. Sit without your instrument, hum or sing a tune, random, made up on the spot. Then pick up your instrument and try to play it. Sounds simple, and for some savant it probably is. But most people will find it difficult. With practice it will become easier and easier.

There are probably many classically trained musicians that can improvise. There are just as many who can't, since it is a learned skill and requires practice, and they probably don't practice this since it is not part of their musical life/background and idiom. Most of them can read the rest of us under the table though! Oscar Peterson was classically trained pianist and could play jazz like there is no tomorrow. His classical skills were evident in his capability to play, and his improvisational skills were epic.

Just 2 cents worth here.

My wife asked if I had seen the dog bowl. I told her I didn't even know he could.