Here are a couple of good points to pick up from “She Thinks My Tractor’s Sexy” by Kenny Chesney, as played by Michael Sanchez. His web site is Violin Tutor Pro.

Joe Venuti used to say he used his first finger as a capo. This made it possible to move anywhere on the neck of the violin and play a lick he already knew. He had the lick ready in a closed position. It could have been Bb. Then, he could go up the neck, to Ab, for example, on the D string, and play the same lick.

The video below shows a way of using the first finger as a capo on the A string to get different intervals on the E string.

You can also notice the interval of the Bb and the Ab. (Not just an A as the player/teacher is saying.) That’s a little  dissonant. That interval is a minor seventh. If he was really playing an A natural it would be a major seventh. Now, that interval is very dissonant! Jazz cats use it.

Michael Sanchez explains the interval of Bb on the A string and G on the E string veru thoroughly. Notice that he really places his third finger very close to the second finger, not the fourth finger.

An excellent demonstration of how to play this lick from Kenny Chesney’s She Thinks My Tractor’s Sexy.