I don't buy a graphics engineer would mistake a video file for an actual demo (running a video file at 40 fps is also bizarre, video files are either 24 fps, 30 fps, or rarely 60 fps). The translated version has the engineers clearly saying the SSD throughput only needs to be in the MB/sec range, not GB/sec. Why in the world would you even bother talking about that over a video file. Sweeney likely has a marketing deal with Sony and doesn't want to rock the boat on that. New AMD GPUs getting outperformed by older Nvidia GPUs in actual practise is nothing new, been happening for ages and Epic already admitted the demo will run fine on a 2070 Super. The PS5 is nothing special GPU wise.
The engineer mentions that they are targeting running that demo at 60fps but they managed to optimise it to reach 40 so far. The presentation was locked at 30, for a very logical reason. 40 fps is a stuttering fest and you don't want to reveal such a demo not running smoothly.