I watched the video and found out to attack a castle, you could use a trebuchet, which is a weapon that throws a heavy ball at the castle.
You could also make them hungry, so that they surrender or dig underneath the castle and take the enemy by surprise.
ln the video, I also found out how to defend a castle.
To defend a castle, the walls need to be at least 17 feet thick and they need extra wooden defences.
further more, they also need to stock up on food so they don’t starve.