Simple they were using a software encoder a Really high detail encoder at a high bit rate. That means it needs MT CPU power. At 50% more cores at nearly the same performance per core between the two systems, the AMD one was able to do the encoding/streaming on the same CPU. When done like this on the 9900K, the system came to a crawl, the game ate so much of the CPU that the encoder/streaming didn't have enough umph to do anything.
Its a stacked example. Lowering the bit rate or using a faster pre-set might not have affected PQ. But it shows what Ryzen 1k did when compared to a 7700k and what I have been doing since I got my 4400+ in 2005. Which is using your system for more than just straight up gameplay, more cores helps. So if you are streamer who wants a super PQ high rate stream. You either have to go HDET or 2 systems with Intel, or do it on one system with a high end consumer Ryzen. What AMD demo'd just before that though was that the 3900x was neck and neck with the 9900k (which wasn't always the case for the 1800x). So it's game at pretty much the same level and do more. The 3900x and 3950x are really appearing to be no compromise CPU's. Negligible performance difference with tons more compute capability to spare. Top it off. I wouldn't be surprised considering Intel if the 3950x and the 9900KS are nearly the same price.
