Feather-sexing is genetic--it doesn't always work. It's like color sexing, but with feathers.
The first one looks like it might be an EE. I didn't watch the whole thing, but the second might be a Black Sex Link. I've never had one, but many females grow up to be black with some copper on their breasts. I'm not sure if the copper would come out as chick fluff, but it it does, then you've got a BSL pullet.
Actually, the feather sexing is only a viable solution if they are a certain breed/cross, if I'm remembering correctly.
I'm not sure of the breed, because there is not a good view of either of them. Can you get pictures in good lighting of both of them? The only way to determine sex this young is if we know the breed and we can sex by color.