After watching, I wonder if the spring is properly connected. (I also wonder if that's the correct carb - have you checked the number stamped/cast on the driver's side of the carb against the manual?)
Remove the three screws on the round black thing and pull it out - it is the temp spring which moved the choke plate. You should see in its housing a metal tab which is connected directly to the choke plate: Moving the tab should move the plate without any slack or hesitation. There should be a slot in the tab which ebngages the end of the spring to move the choke. If this is broken or not properly engaged, the choke will not work properly. When it is properly engaged, rotating the spring holder should also move the choke in either direction. When it does, turn it until thye choke just closes and then replace and tighten the three screws. You choke stove looks properl;y installed and should work. Your unloader diaphragm also looks properly hooked.

--johnny