This video explains hypersonic weapons in the general sense. But the threat is from the newer advanced hypersonic weapons that are steerable at low altitudes. There is no "I know where it is going and can intercept" as the speaker claims since where it is going changes dynamically.

I hope I am the one who is misunderstanding the technology but every time I see someone talk with absolute certainty or with an appeal to authority they are often wrong some way.