To those who are against filming on an aircraft, it would be one thing if the FA asked the OP nicely to stop filming and he rudely replied back & continued to do so, it's another in this situation. Maybe it's just the usual German hospitality but it sounds like the FA rudely told OP to stop instead of a simple "Sir, we unfortunately do not allow video recording on the aircraft" or "Unfortunately it's our policy to not allow video recording, we apologize".