So how does the farm trick work?

You left shift and put the mouse pointer over the grainary and then right click?

No, that doesn’t work. This is the ‘put down a bunch of farms in a hurry’ trick. I’ve tried a bunch of times and it only seems to work sporadically, I must be doing something wrong.

You place buildings with left-click. Shift+left click in center of building will automatically add farm to nearest possible location,

As someone said, it is shift + leftclick howering over granary/town center. But it only works for 1 layer of farms, for the 2nd layer you have to move your mouse around the 1st layer farms.

In that video IamMagic shows and tells how to do it.

That is very slick.

Is there a smooth way to tell each of a group of villagers to grab their own farm or do you have to do it one at a time? Grab the vill, click on the farm, grab the vill, click on the farm?