Is it possible to do “at-home” vent sexing?

[BlueBaby]

I was just at youtube and maybe a few more should learn how to do it.

Chick Sexer – The $60,000 a Year Job Nobody Seems to Want

 

[CatchaTorriFarms]

Is this always true with all breeds? I keep reading that its a breeding thing to be bread into them. Assuming second generation birds as well?