Why is my AIO cooler making a loud humming noise under load?

Yeah, I agree with TechWhiz12. Since you just installed it a couple of weeks ago, hopefully it’s not anything major. Have you noticed if the fans ramp up a lot more than when you first set it up? Sometimes, when the system gets hotter or has to work harder, the cooling system reacts with more intensity, and that can lead to some strange noises. Keep an ear out for any vibrations as well, they could be the culprit.

It sounds like your AIO might need some air purging, or possibly the pump is starting to wear out. It could also be that something loose is vibrating, but it's tough to diagnose just from a video. Also, if your thermal paste has gone bad or if your radiator is clogged with dust, that might cause increased noise when under load. How does it sound to you? Does it still seem like an owl, or just loud fans doing their thing? You just installed it, so that might rule out a lot of issues, but it's worth checking out as well.