This is a Remote Control Weapon Station comparable to the Mk38 mod2 used on the Webber Class WPCs. There are many such systems, but I am highlighting it because it is already in use on a boat much smaller than the Webber class. The Combat Boat 90 (time 7:10 in the video above) is only 53 feet (16.1 meters) long and 22.6 tons full load. That is about one quarter the displacement of the 87 foot Marine Protector class, less than one fifteenth the size of a Webber class. It actually displaces a little less than the 45 foot Response Boat, Medium (RB-M). I particularly like that this system has been mated with the 30mm M230 chain gun from the Apache Helicopter that is capable of penetrating light armor (see below). That could give us serious penetrating power.
Like most of these systems, they incorporate electro-optic devices which can be used for SAR, target identification, or to enhance navigation.
Thanks to Lee for bringing this to my attention.