Mage, I haven't seen the video 'link' yet but I understand the questions you pose from it. Here's the list and if I've omitted anything, let me know:
So your saying Christians find global genocide, child murder, condoning slavery, condemning people for something someone else did, punishing an innocent instead of the guilty, and disproportionate punishment to the crime all acceptable?
I think this is what you're asking? Why do Christians believe in God who to you is nothing more than a 'blood thirsty tyrant'?
I'll start in Genesis with the 'fall of man':
Genesis 3:22...God said,"The man has now become like one of us.. knowing good and evil. He must not be allowed to reach out his hand and take also from the tree of life and eat, and live forever."
23) So God banished Adam from the Garden of Eden to work the ground from which he had been taken.
24) After He drove the man out, He placed on the east side of the Garden of Eden cherubim and a flaming sword flashing back and forth to guard the way to the tree of life.
On to Cain's story:
Genesis 4:3 In the course of time Cain brought some of the fruits of the soil as an offering to the Lord.
4) But Abel brought fat portions from some of the firstborn of his flock. The Lord looked with favor on Abel and his offering,
5) but on Cain and his offering He did not look with favor. So Cain was very angry, and his face was downcast.
6) Then God said to Cain, "Why are you angry?" "Why is your face downcast?"
7) "If you do what is right, will you not be accepted? But if you do not do what is right, sin is crouching at your door; it desires to have you, but you must master it."
8) Now Cain said to his brother Abel,"Let's go out to the field." And while they were in the field, Cain attacked his brother Abel and killed him.
(skip to verse 10)
10) God said, "What have you done? Listen! Your brother's blood cries out to me from the ground.
11) Now you are under a curse and driven from the ground, which opened its mouth to receive your brother's blood from your hand.
12) When you work the ground, it will no longer yield its crops to you. You will be a restless wanderer on the earth."
13) Cain said to God, "My punishment is more than I can bear.
14) Today you are driving me from the land, and I will be hidden from your presence; I will be a restless wanderer on the earth, and whoever finds me will kill me."
15) But God said to him, "Not so; if anyone kills Cain, he will suffer vengeance seven times over." Then God put a mark on Cain so that no one who found him would kill him.
16) So Cain went out from the LORD's presence and lived in the land of Nod, east of Eden.
(Nod means wandering).
Two age-old questions are present here and later w/verse 17 that speaks of Cain's wife.
question #1 what other people was Cain afraid of because up to this point the Bible has only mentioned Adam, Eve, Abel and Cain?
Genesis 1:27) So GOD created man in His own image, in the image of GOD he created him; male and female He created them.
Genesis 1:28) GOD blessed them and said to them, "Be fruitful and increase in number; fill the earth and subdue it. Rule over the fish of the sea and the birds of the air and over every living creature that moves on the ground.
Then in verses 29 and 30 GOD tells 'them'..."everything that has the breath of life in it--I give every green plant for food."
So back to the people. Adam, named everything and also named Eve. In Genesis 3:20 it tells us why, because she would become the mother of all the living.
The Bible mentions the fist born 'male' child as being Cain and this is what Eve says in
Genesis 4:1, "With the help of the LORD I have brought forth a man."
Verse 2 mentions the birth of Abel.
Genesis 4:25 Adam lay with his wife 'again', and she gave birth to a son and named him Seth, saying "GOD has granted me another child in place of Abel, since Cain killed him.
