"I know this is a weird post but I just wanted to share these to always remember my incredible empathetic little mini.
"Life is infinitely better with her in it. I miss u, jack. we miss you a lot. (sic)"
One video simply showed the white box with Jack's ashes and a stuffed teddy bear wearing a purple bow.
Chrissy - who also has 2-year-old son Miles with husband John Legend - explained: "his is the cutest, most beautiful thing I have ever seen. We just got baby Jack's ashes back, so they're in here for now with some blessed, holy tie string.
"And Luna put a little therapy bear around him and the best part is I came down and she gave him a piece of her favorite snack, a tiny piece of Pirate's Booty... She's amazing."
In another video, Luna was seen petting the bear as she said: "Hi guys.
"Hi, this is baby Jack, and I'm Teddy. I'm Luna. How are you doing today?"
Meanwhile, Chrissy previously revealed she was told she could have died during childbirth when she suffered her devastating pregnancy loss.
She said: "My doctors diagnosed me with partial placenta abruption. We monitored it very closely, hoping for things to heal and stop. In bed, I bled and bled, lightly but all day, changing my own diapers every couple of hours when the blood got uncomfortable to lay in.
"My bleeding was getting heavier and heavier. The fluid around Jack had become very low - he was barely able to float around. At some points, I swore it was so low I could lay on my back and feel his arms and legs from outside my belly."
Chrissy was then given the devastating news that Jack "wouldn't survive", as doctors warned her that if she carried on bleeding, there was a chance she could lose her own life as well.
She added: "After a couple nights at the hospital, my doctor told me exactly what I knew was coming - it was time to say goodbye. He just wouldn't survive this, and if it went on any longer, I might not either.
"We had tried bags and bags of blood transfusions, every single one going right through me like we hadn't done anything at all. Late one night, I was told it would be time to let go in the morning."
Where to get help:
• For support for bereaved parents visit sands.org.nz
• 0800 543 354 (0800 LIFELINE) or free text 4357 (HELP) (available 24/7)
• https://www.lifeline.org.nz/services/suicide-crisis-helpline
• YOUTHLINE: 0800 376 633
• NEED TO TALK? Free call or text 1737 (available 24/7)
• KIDSLINE: 0800 543 754 (available 24/7)
• WHATSUP: 0800 942 8787 (1pm to 11pm)
• DEPRESSION HELPLINE: 0800 111 757 or TEXT 4202
• NATIONAL ANXIETY 24 HR HELPLINE: 0800 269 4389
