His jaw chews down and back consistently and there is no tremendous breath pressure as the music becomes more and more dramatic. Many tenors could learn how to handle this piece by watching this video. This stretches the appropriate space for the extreme high notes. The secret for the tenor is not to do this too early in the scale. Because his jaw is back, his upper register flips into the tenor extension.
Many tenors dream of such a smooth transition and the secret is right on the video tape.
It is a great example of how to handle the Italian 'ee' vowel with the rounded mouth position. There is not much to say about this piece. It is an audience pleaser. The following list is of concepts to remember that I noticed in the singing of Jussi Bjoerling. There is always a slight curve in the neck without the weight of the head 'crunching' the spine.