This is an example of how to improve the aerobic system by using the High Intensity Continuous Training method (HICT). Unlike HITT, where the intensity is high/volume low, HICT training keeps intensity high/volume high.
The exercise here is using a heavy weight vest and performing controlled, paced step ups, for 10-15 minutes. This type of conditioning works on improving the oxygen utilization of your fast twitch muscle fibers. Why is this so useful? Genetically we are all born with a specific ratio of fast twitch to slow twitch fibers. By using this method we can improve the endurance of our genetically predetermined fast twitch fibers by making them more efficient at using oxygen to create more ATP (currency of energy).
This is incredibly useful for individuals that use fast twitch fibers, sprinters, power lifters, to name a few. If we can improve the fast twitch fibers endurance we can prolong their effectiveness at performing the necessary activities that demand their usage.
As a side note, they're rather boring, which is why I listen to an audiobook during it. All though Metallic is welcomed as well.