Sexing seeds is this too good to be true?

This vid on you tube makes sexing seeds easy, I've been growing for 45 years and never heard of this method, what's your opinion fellow growers? TIA

yes. too good to be true.

That is just a bunch of BS no way to know the sex of seeds nuless you rev, a plant to get fem seeds.There was a con artest here in ky, trying to sell a liquid he said soak your seeds in it and it would kill the male seeds and onley your fem, seeds would grow.I did not buy it but a few people did and it was no good as I told them it would not work,but I got to make fun of them for a few years over them being coned.

This is beyond BS. The earliest way to tell sex these days is by submitting leaf samples to labs that offer this service and its not cheap either..