Puzzle designer, Tony Fisher, has now uploaded a video where he demonstrates more moves on what is being claimed to be a 100x100, in the video, he turns a few layers on one side and then rotates the cube to turn a few layers on another side. He also counts each layer on one of the edges to confirm there are 100 'pieces' there
Ultimately we will have to wait and see whether this is legitimate or whether it is another prank, to prove it is legitimate, he will have to put the cube in a checkerboard pattern, it is understandable that this might take some time with such a big cube.
It is worth noting that so far we have only seen a few layers turn and only layers with red facing top and green facing top. Jacob Cubing appears to be pretty confident it is fake from his video comments, he is rumoured to be working on a 50x50 or 51x51 so if the 100x100 was real then his progress would be completely wasted.