What a rediculous video. And repetive of dozens of others. No, he is a fool. Or a liar.
"Dipping the nose down" , or more accurtely pitch attitude relation to altimetry is complete nonsense. More of a strawman as altimetry in aviation has nothing to do except in limited circumstances, with geometry/ maintining an absolute height above a surface, it is about maintaining a reference pressure altitude. This would be true even if the world is flat. Even flat earthers dont deny that an atmosphere exists do they?
There is nothing such as "upside down" on a planetary scale.