In the linked video, Czech police officers demonstrate that neck kneeling is an effective form of restraint that still allows the suspect to breathe.

In a real scenario the officer would be pressing much more force on the suspects neck than what is presented in the video. The placement of the knee is another important factor. Because we see in the video that the training partner is lying completely still and not giving up much of a fight. Why aren't they demonstrating a scenario where the suspect is trying to break the restraint?

The upload date and content is also a direct response to the killing of George Floyd. It was uploaded not too long after his death. They even make a passing mention of it in the video too. This is clearly a video meant to push a narrative of policing techniques that don't actually work.