That boy looks a lot like my nephew and he still does that.
My nephew is around that same age and still in diapers and his parents let him do what he wants basically.
I remember him fighting me over a piece of pizza a few months ago and I finally got fed up with it and spanked his butt after I removed the diaper first.
I pulled his pants off, took his diaper off and spanked his butt with a belt and he got really mad, but it seemed to help.
I let him know that I was not gonna tolerate that stuff, when he was over here at my house and I don't care what his mom or dad says.
You can't let a kid just do what they want, or they will turn out bad when they get older.
I got spanked as a kid and I spank my kids when they need it as well and I turned out just fine and my kids are turning out just fine.
Sure you're kids are gonna hate you at first for spanking them, but the hate won't last long.