Because they showed it in the Microsoft's Xbox conference. I have the uncompressed version of both and there is clearly a resolution difference between this and January footage, compare the characters faces for example, Jan video they are so crisp and detailed while in this one they are pretty blurry and not that detailed. There are also no wind effect on Igni sign where we can clearly see in the NVIDIA conference footage. These are my reasons for not believing that they re not the same PC footage and this one is Xbox. So i believe there is a misunderstanding or i dunno smt like that
The reason igni effect is different is because those are two different igni spells. The one in the Nvidia video is a violent burst of energy, while the one in the new video is a more of a channeled stream.