Movement and dance play a huge role in this performance. If you were only listening to this piece, you would have a different reaction. With this specific recording, you would be confused about the laughter. If it was a studio recording, the music would sound much more serious and dramatic. Although, there are a few humorous moments in the music. For example there are a couple of big tuba notes/splats. Yet, it is the dancing that makes this performance humorous. Clearly, these men are not dancers and it is funny to watch them try. Still, they do quite a good job. The choreography and music are memorized and the music still sounds fantastic. The Canadian Brass are an excellent example of how to use movement in a performance effectively. Their website describes them perfectly:
"Masters of concert presentations — from formal classical concerts to music served up with lively dialogue and theatrical effects — Canadian Brass has developed a uniquely engaging stage presence and rapport with audiences. Whatever the style, the music is central and performed with utmost dedication, skill and excellence. The hallmark of any Canadian Brass performance is entertainment, spontaneity, virtuosity and, most of all, fun."
I especially like the part "Music is central and performed with utmost dedication, skill and excellence." Movement does not detract from their art. The members of the Canadian Brass are highly respected by musicians and they can entertain the masses. Movement in this case, made the performance humorous and accessible.