While I am not a horn player (or any other instrument so I have been told), I believe he is using a Monette ... not sure which model. You can find the horns at:http://www.teleport.com/~monette/.
Marsalis's horn on "JAZZ"
Has anyone noticed the horn that Marsalis is using on the Jazz documentary? It appears to be some kind of "moulded " design rather than having distinct tubes of bent brass. This is probably some common thing to you that can actually play such an instrument, but, I have never seen a horn like this. What gives? Can any players enlighten me?