https://pubs.acs.org/doi/10.1021/acsami.1c02368
In the first video, on a 73f day, commercial white paint was 84.9f, 10.9f warmer than ambient temperature. The Barium white paint was 70.7f, passively cooling 2.3f below ambient temperature. Certainly not the ideal example but it proves the concept.
The difference is you can passively cool something over 15 degrees below ambient temperature using zero energy to do so. Commercial white paint won't do that to that extent.
It's possible because according to the second video infrared light in the 8-13 micrometer range radiates heat past the atmosphere directly into the cold vacuum of space. Instead of that heat being reabsorbed in the immediate surrounding area. Tuning the reflective wavelength of your material to this range provides passive cooling.
There are other ways to this that don't require paint.