New pc - Help me understand what is wrongly connected

Job ID: 37642903

Budget: $10 – $30 USD

Hi there
I have a new PC configuration that I connected myself but the PC won't turn on.
Neither the fan or any light on.
Power is on, button is turned on
And it seems I connected every thing right

Help me understand with the video :
https://we.tl/t-HBk1NSQ5Jq

Photo attached is what cable is not connected. On the left PCI-E (for graphic card ? I don't have one)
And on the right, something coming from the inside of computer tower..don't know is useful or where should I connect it