Well these are probably confirmed stats for the light Brig and normal Brig as shown on the video. For the war brig we will have to guess comparing it to other ships.
Light Brig
Brig
War Brig:
Brig and Frigate got the same amount of cannons, shipmates and cargo. That automatically would make war frigates and war brig have the same amount of cannons - 14, cargo - 16 and shipmates - 12. It will have less hull and weaker sails than a war frigate however it will be faster than it - 10 knots(same as sloops). War brig will also have more broadsides then a war frigate.
[Credit goes to LEO]