Cheryl Korbel said the "horrendous" sound of the shot, which went through her wrist then hit Olivia Pratt-Korbel, would stay with her forever.
Thomas Cashman is accused of being the gunman who carried out the attack in Dovecot, Liverpool, on 22 August.
The 34-year-old denies the murder of Olivia and is on trial.
Manchester Crown Court heard how the gunman fired through the front door of the Korbel family home just after 22:00 BST.
He had been chasing Joseph Nee, who is said to have been the intended target, through the street, the trial heard.
Ms Korbel often became emotional in the 50-minute video, which was recorded with a police officer a week after the shooting and showed her right arm was bandaged with a visible blood stain.
Many of Olivia's family cried as they listened to her testimony.
Ms Korbel said: "[It was] horrendous. Horrendous... It was like off a movie.
"The sounds that they make... it was the sound of it going through my wrist as well. It's hard to explain the sound."
Mr Cashman watched the video inside the glass-walled dock.
At one point he wiped away tears with his hand and a dock officer gave him a tissue during Ms Korbel's interview.
Ms Korbel told police she had heard bangs outside her home and when she went outside to look, she saw a man coming up the road.
She said: "Then I spotted this other lad behind him, dressed all in black, couldn't see his face or nothing, and I realised at that point that it was gunshots because, like, the other one was running after him.
"At that point I realised he was running towards me so I ran back to the house."
Ms Korbel said she closed her front door but it did not shut properly because it was left on the catch.
Speaking through tears, the mother-of-three, said: "I tried to keep hold of the door, I was just screaming, screaming to go away and then I heard the gunshot and I realised, because I felt it hit my hand.
"I couldn't keep the door shut because it wasn't locked, and with my hand I couldn't keep it shut, so I let it go and I think at the same time I heard the baby [Olivia] speak and that's when I turned round and I spotted her sat at the bottom of the stairs.
"I leant over her and like held her to the left, I just huddled over."
Ms Korbel said her son Ryan helped her to carry Olivia up the stairs and she shouted for a towel to stop the bleeding.
She added: "Ryan turned round and said to me 'Mum, I can't do this' so I tried to move the baby again up to the top of the stairs.
"I heard the lad downstairs shouting 'please lad, don't' and I heard another gunshot.
"I couldn't keep her awake."
She added: "[Olivia] went all floppy and her eyes went to the back of her head and I realised that she must have been hit because I didn't know until then and I lifted her top up and the bullet had got her right in the middle of the chest."
She said a neighbour came in and started CPR on Olivia.
She added: "I knew she'd gone. Then the police turned up and came up and just picked her up and took her out the house."
Ms Korbel said she was taken to hospital for treatment to her hand and while she was there, she was told Olivia "had gone".
"I just went hysterical screaming I wanted my baby," she said.
She described a phone call with a friend who was with Olivia at Alder Hey Children's Hospital.
Ms Korbel told police: "She told me she was with the baby and I told her not to leave her on her own and she promised me that she wouldn't.
"She said she looked like she was sleeping, so I made her promise she wouldn't leave her on her own."
Asked to go through the incident again by a detective taking notes, Ms Korbel said time seemed to slow down as she saw the gunman and another man run towards her.
She said: "Although they were running, it was like it was in slow motion.
"My wrist was, blood was just squirting everywhere. I screamed, 'I've been shot'."
Ms Korbel said she thought she heard Olivia say "mum", and when she turned around her daughter was sat on the second step of the stairs and did not realise what had happened until she carried her daughter further up the steps.
"She was gasping for breath," Ms Korbel said.
"I was screaming for her to stay with me. There was blood everywhere. I kept saying it was mine... but I knew it was not right.
"So I lifted her top, then that's when I realised she had been shot in the chest.
"I was just screaming, 'Please Liv, stay with me'."
After the video finished, the judge, Mrs Justice Yip told the jury: "I'm conscious that this is difficult evidence - I know that you will put your emotions aside when you consider your verdicts but that doesn't mean that we don't feel emotion, and I'm conscious that this is difficult."
Earlier the court heard how Mr Nee, the intended target of the shooting, shouted "please don't" as his friend ran "for his life".
A police interview with Paul Abraham, 41, who was with Mr Nee when the gunman opened fire was shown to the jury.
He said that he and Mr Nee had left a friend's house that evening when he heard loud bangs.
He said: "Both of us ran. One must have got Joey.
"He fell over. I don't even know when he got shot, he just fell.
"As he rolled over I just basically jumped over him and went through a gate."
Mr Abraham said he saw Mr Nee continue running up the street, and the attacker, with two hands on what he thought was a gun, walking up the road.
He said: "As I was going up the entry [Mr Nee] was saying 'please don't', I heard him shouting 'please, don't'."
Mr Abraham said he thought he heard two further bangs as he jumped over fences of back gardens to get away.
He said: "I was just running for my life, basically."
Mr Cashman, of Grenadier Drive, West Derby, Liverpool, denies the murder of Olivia, the attempted murder of Mr Nee, wounding with intent to do grievous bodily harm to Olivia's mother, and two counts of possession of a firearm with intent to endanger life.
The trial continues.