If it is an existential question, the flat Earth comes out funny, since space is 3-D, which is also spherical. The informative video mentioned "spherical radiation", as in "spherically radiating sunlight", which is true, there is that, and that's something something, and this type of radiation says a lot about the nature of space, even as pure or absolute space.
If in principle all numbers themselves are as three dimensional as pure space, then the Earth would be odd or unnatural to be flat, since it is a number too. Numbers are three dimensional in all space, and in abstraction too, in the sense that there is always more or less in the relation ... the relation of position ... or any opposition.
Since position is relative to six cosmic directions in one, for seven in the middle, the relation of more or less in all things is complete in 3-D; and the best relation of pure space to the infinite is in 3-D also. So if the Earth is flat, it is a strange tension for it to have in the great circles of 3-D space, where so many other things are round and full.