Alas, the CMFI trailer is not based on an actual battle. When I made the trailer I had to construct an almost entirely new map to suit my purposes. I then designed a battle with a lot of different units to both sides, as BFC would like a trailer that would showcase the variety of units available in the game.
Actually, if you look closer you´ll see that´s Clint Eastwood - but otherwise you´re not too far off. 😀 Most of the "action" is staged for the purpose - not part of an actual game. I played both sides and used a lot of short covered arcs to control who was firing at who.
So there has never been a playable scenario of this battle - but I did upload the map. It is still in the Scenario Depot: http://www.thefewgoodmen.com/tsd3/cm-fortress-italy/cm-fortress-italy-add-ons-maps/cmfi-movie-map/
Edit: the download link in TSD may not work. In that case use this link:
https://www.dropbox.com/s/giv78q7brpvzelm/CMFI Movie map.btt?dl=0