They test against scenes where the PS5 is not hitting 60 because if you have a frame cap of 60 then there is no way to know if there is performance being left on the table because of the cap.
I work in clinical research within data management. In my industry, we have to check multiple scenarios - if something goes wrong one way, we check for it, but we also have to check for the reverse situation. Otherwise we risk concluding on limited data. If a laboratory result is 3x the normal range, we wouldn't look at that result and conclude that the study drug had a dose limiting toxicity, we'd check for other concomitant medications, related adverse events, etc. Define what's causing the data to appear that way.
The last video appeared to determine that there was a bandwidth contention causing framerate drops (agree, the image of a single car with alpha effect doesn't looks like it's maxing out the rendering hardware), but we can't then perform the same test on a 2060S and conclude that the PS5 and the 2060S are broadly similar in their rendering performance in that situation, as the test wasn't measuring the rendering performance of the cards. It highlighted bandwidth contention - which Alex pointed out, but he then went on to conclude that they're broadly similar in rendering performance (which may be true, but that test certainly did not confirm it). The were a few other points that looked like they were from the same situation/scene where the 2060S also dropped frames, but again looks like similar kinds of issues that are perhaps unrelated to rendering performance.
It appears that a lowered framerate situation was determined from the consoles and then moved on to test from that situation alone. We didn't have the reverse situation; were the framerate drops were identified on the PC hardware and compared that back to the PS5. All we have is a demonstration of the proportional difference in bandwidth contention.
I definitely agree that finding framerate drops usually determine the rendering performance, only that this test did not do that. Which appeared to be acknowledged by Alex, only no significant further testing was performed and he instead decided a premature conclusion was that the PS5 was a little above the 2060S. Regardless of whether it is or is not broadly similar, the demonstrated results are inconclusive.
(even the Watch Dogs Legion video wasn't a great example, as it was essentially a RT test and it was limited to 30hz with no deviation)