What you need
Four things go in with the beans: a tablespoon of sugar, black pepper, salt, and a fourth of a cup of bacon grease, and she is specific that it is bacon grease and not butter (the four ingredients). Hers is saved from hickory smoked bacon, and the beans are two cans of the family size, regular cut, not French style (the beans and the grease).
She cooks them in her number 12 cast iron, which she says is well seasoned and makes the best of them, but a big pot or whatever skillet you have will do the job. She does recommend getting a cast iron pan, calling it the main thing that starts a good kitchen (the skillet she uses).
How she starts them
The first thing is draining half the juice off the cans. She does not want all of it in there, but half of it stays (draining half the juice). Both cans go into the skillet with that half of the juice, and the heat goes to medium (both cans into the pan).
Black pepper goes in first, and since they like a lot of it she puts in probably a good teaspoon (a good teaspoon of pepper). Salt goes in next; she does not give an amount for the salt on camera (salt, then the secret).
The two things people leave out
The first is white sugar, and she names it as the secret outright: a tablespoon of it for two cans, or a teaspoon if you are only cooking one (a tablespoon of sugar). She says the little bit of sugar is what people wondered about in their granny's beans (the ingredient granny used).
The second is the bacon grease, a fourth of a cup of it. She says olive oil or butter will work, but for true Southern old style green beans like granny made you have to pull out the bacon grease (the quarter cup of bacon grease). Once the beans start heating up she gives them a mix to get the grease worked through all of them (mixing the grease through). She adds that you can open a can of green beans and throw a little butter in, but they will not taste anything like these (why not just butter).
Cooking the juice out
Everything after that is cooking the juice off. She turns the heat up, brings them to a boil, and says all of that juice has got to cook out (bringing them to a boil). While it boils down, the seasonings are soaking into the beans (what is happening while it cooks).
Keep them going past the point where you want to stop. She says to let them run until the skillet is getting dry and you start to hear a sizzle, almost like you are frying them, and just not to let them burn (listening for the sizzle). When they are done there is no juice left at all, they are wanting to stick without sticking, and the shiny coat on them is the bacon grease (how they look at the end).
What can go wrong
The mistake she owns up to is stirring. It is Travis's tip, passed along on herself: stir them every once in a while so they do not burn, but do not keep stirring them, because stirring too much turns them to mush (quit stirring them so much).
She also checks the beans as they heat for any stems that might have been left in the can (checking for stems). And she is patient about the timing, saying at one point that you are going to want to turn them off before it is time (it is not time yet).