The guy who made that must have been wearing the most elaborate tinfoil hat of 2016.
What starts out as an interesting update on fairly recent geophysics discoveries quickly spirals into lunacy.
A high gravity region is caused by material that has higher density than its surroundings.
So to suggest any kind of man-made or alien object, which would therefore require a hollow cavity of some sort (therefore much less dense), is absurd and is completely contrary to the higher gravity readings. Unless this underground superstructure is made of metal with metre-thick walls. Also absurd. Consider the largest man-made civil engineering project on earth - the three gorges dam in China - which is nothing compared to the apparent goliath underground Nazi base hidden from the entire of humanity under Antarctica for several decades...
It's rather obviously a standard geophysical process.
Also... "UFOlogy" ... haha. Right up there with horoscopes and deistic religion.
There is one universe where this happens all the time, and that is in the game Space Engineers - where you have artificial gravity but it comically doesn't obey Newton's 3rd law. This can only be one thing: Space Engineers drones have hacked out of the game and into our world, like in Tron. We are being invaded by NPCs! And you know what that means? Skyrim's guard are coming to get us for shooting all these arrows to their knees!