An ice wall is just a wall of ice. (As the name implies) Therefor, he has shown you an ice wall. The FET ice wall however, is Antarctica and is at the edge of the known world.
FET implies that bendy light or electromagnetic acceleration causes light to warp in a way that causes the Earth to look round. Hence, you could not see the edge of the world from your position, nor use a telescope to magnify it, since a telescope doesn't really move your coordinates, it just makes things look bigger. Also, pictures can be doctored, no matter how old or new, so you can't really use them as evidence.
The Earth looks round, whether by bendy light, or by its supposed curve. You can't really disprove neither side, unless you build, say, a 35 mile long metal beam. But I guess the beam would bend anyways either by warped light in FET, or by the curvature of the Earth in RET.