I use narrow definition of atheism, because wider definition of atheism can NOT be contrasted with agnosticism.
If someone is saying "I am not agnostic, but atheist", he clearly means "atheist" in a narrower sense of atheism.
Yes, we may put the author of this video into "Agnostic atheism" bucket. But he still would be in the "agnostic" camp (which he denies).
Regarding "Earth will just keep rotating" theory: that theory is scientific unlike "god does [not] exist" theory (because it is not falsifiable) .
Believing in proved scientific theory is not faith.
Believing in something not-provable is faith.
I never was a theist, but as a child I was an atheist (in the narrow definition of word "atheism").
I know the difference between agnostics and atheists. The difference is faith.