I don't think the video by itself says anything. It's just showing how they tested the tire.
If you're referring to the actual test results:
https://www.bicyclerollingresistance...-marathon-2015
Then, it shows that the 35mm Kojak has higher rolling resistance than the 37mm Marathon. However, narrower tires need higher air pressure, but according to the results even with a 15psi difference the Marathon still performs better.
I found this PDF showing the Marathon performing better than the Kojak at the same air pressure, although ideally the Kojak should be inflated to a slightly higher pressure.
https://s3-eu-west-1.amazonaws.com/f...t_schwalbe.pdf
I've never used tires as narrow as those though. In the past I tried the Big Apple 50mm, Marathon Supreme 42mm, Energizer Plus 47mm, Marathon 47mm, and currently the Big Ben Plus 55mm. I now always use tires with the Greenguard for the puncture protection. I almost never get punctures now, only perhaps once the tire ages past 2 years, or if I run over a nail, or something hits the sidewall. I remember in the past riding a non Greenguard tire which had a puncture from a small staple. But the Greenguard will add some rolling resistance. I also use the wider tires for the higher load capacity and softer ride. Even the 55mm at 3 Bar vs 47mm at 4 Bar feel very different, with the 55mm being much less painful on bumpy surfaces. Wider tires generally have lower rolling resistance at the same pressure, but it also depends on the structure and properties of the tire shape and material, or at least that's what I read on blogs and forums.
For me, the puncture protection is more important than the rolling resistance, because I don't want to be caught with a flat and waste a lot of time unloading my cargo with all the straps and the wheels to repair the tube.