The bit I gleaned was the claim that since 60GHz is absorbed by oxygen (haven't checked this, but I'd assume similar to 2.4GHz being absorbed by water), it therefore interferes with your lungs' ability to intake oxygen. (my low-effort analysis: the radio waves won't penetrate your skin by more than a few millimeters, and therefore could in no way act in your lungs)
The whole narrative was much jumping around making connections that would seem plausible if you don't know or try to investigate technical details. For example - a defense contractor worked on 60GHz gear as well as communications for cruise ships -> smoking gun!
I'm sure there was plenty of innuendo that rolled right off my back, but makes an emotional impression. My aunt had gotten the impression that 5G is 50-60 times the power of a microwave oven. I couldn't bring myself to watch the video again to find what could possibly be interpreted this way, but I'm guessing it was talking about the frequency while implying magnitude.