Please know if you do this improperly you can and will cause injury to the ducks and geese. It takes practice and a light hand to not hyperextended the genitals causing injury. Please tread lightly when first trying to do this.
Yes, that is star advice.
However, it does have to be said, that even "expert" sexers began somewhere. And for those who only have backyard flocks (as opposed to the gazillion Metzers deal with!) this is still a very informative and valuable post/link.
I can honestly say, the Metzer video has been the
most informative sexing advice I have stumbled across (thanx to the OP!). Even Mr Metzer admits that he didn't get it right from the word go and it takes much experience to perfect sexing.
What I liked most about this video (compared to the pictoral advice I'm used to seeing) is, that it not only emphasises that it is not a downward pressure exercise, but a gentle "unveiling" one; coupled with a number of examples (which, to be honest, left to my own devices, I can totally understand how mistakes could be made!).
Of course, a heavy hand will cause injury (if not death!) but, the people reading this are here to learn, not inflict unnecessary suffering or injury.
Better to be guided by an informative video (with necessary cautions contained therein) than to be posted a pictoral example without those cautions of experience included
That's my take on it.