I also believe this to be Augusta harbor. The following is from the book Courage Alone by Chris Dunning:
"In July [1943] the [83 Gruppo RM] had twenty RS14B's, four ZB06Bs, two Z506S, a single Z501 and a Breda 25 with 170 and 186 Sq. Twelve of these were operational... On 10 July one RS14B and one Z506 B were destroyed by battery fire, but on 22 July the Allies managed to capture all the other aircraft intact in the bay."
Dunning, Courage Alone. Hikoki Publications, 1998. p. 110
In the clip at 17:15 you can also see the damaged Fiat RS14B that Dunning is likely describing. I will try to find more info/pics to confirm this.
Great footage by the way, thank you for sharing!