Is salvation of God or man? Your view on this is baffling coming from someone claiming "the doctrines of grace"
That video just proves children learn from watching and listening to those around them.
People here claim children are born telling lies, but they ALWAYS speak the language of their parents. No child of English speaking parents speaks Spanish or any other language, they ALWAYS speak the exact same language as their parents. So if they lie, they learned it from listening to their parents and siblings.
Little children can believe in Jesus, Jesus himself said so.
Mat 18: 2 And Jesus called a little child unto him, and set him in the midst of them,
3 And said, Verily I say unto you, Except ye be converted, and become as little children, ye shall not enter into the kingdom of heaven.
Mat 18:6 But whoso shall offend one of these little ones
which believe in me, it were better for him that a millstone were hanged about his neck, and that he were drowned in the depth of the sea.
We can see in context that Jesus was speaking of a very small child, small enough to be picked up and placed in the midst of his disciples, and Jesus said these children BELIEVE IN ME.