This is a pretty Christmas medley of "Silent Night" and "Away In A Manger" arranged for Brass Quintet by Eddie Lewis. 

The arrangement is classical, but the harmonies lean a little towards the jazz side. The hint at a jazz sound adds a warm spicy flavor to the piece, reminiscent of the aromatic textures of hot chocolate in front of a log fire, fresh pine needles, and grandma cooking Christmas dinner in the kitchen.

There are nine chords and minor dissonances, but nothing that makes the piece distinctly sound like jazz.  So, it is to be performed in a classical style despite (or in celebration of) the hint of jazz.